中级微观经济学范里安版本2-5章习题

中级微观经济学范里安课后答案第1章市场说明：作为范里安《微观经济学：现代观点》教材的第一章，本章通过考察一个特定的市场模型——住房市场进行实例分析。

对于本章内容，建议学员简单了解即可。

钟根元《中级微观经济学学习指南》（第4版）未添加相关的练习题。

第2章预算约束一、判断题1考虑某消费者消费价格均为正的两种商品。

如果其中一种商品的价格下降了，而收入和另一种商品的价格保持不变，那么预算集范围缩小了。

（）【答案】F查看答案【解析】设消费者消费x和y两种商品，价格分别为px和py，收入为m。

设商品x的价格由px下降为px′，那么，如图2-1所示，预算线与横轴的交点由m/px右移至m/px′，预算线与纵轴的交点未变，显然，预算集的范围扩大了。

图2-1 价格下降引起的预算集变化2以横轴代表商品1，纵轴代表商品2，商品1价格为p1，商品2价格为p2，那么预算线的斜率为－p2/p1。

（）【答案】F查看答案【解析】如图2-2所示，预算线的斜率k＝－OA/OB，A为预算线与纵轴的交点，表示的是收入全部用于购买商品2时的消费量，即OA ＝m/p2，同理，OB＝m/p1，因此预算线的斜率为k＝－（m/p2）/（m/p1）＝－p1/p2。

图2-2 预算线3如果所有的商品价格都变为原来的两倍，而收入保持不变，那么预算集没有变化，因为相对价格没有变化。

（）【答案】F查看答案【解析】预算线方程为px＋py＝I，价格变为原来的两倍后，预算线变为2px＋2py＝I，或者px＋py＝I/2，显然，预算线斜率不变，但预算集范围缩小了。

4考虑两种商品，如果一种商品价格为正，而另一种商品价格为负（例如把“拾垃圾”也看成是“商品”，负的价格表示对消费者的补贴），那么预算线斜率为正。

（）【答案】T查看答案【解析】预算线的斜率为k＝－p1/p2，若一种商品价格为正，另一种商品价格为负，那么－p1/p2＞0，即预算线斜率为正。

5如果所有商品价格变为原来的两倍，收入变为原来的三倍，则预算线会更加陡峭。

范⾥安《微观经济学：现代观点》（章节题库-选择）【圣才出品】第5章选择⼀、判断题 1．某消费者的效⽤函数为u （x ，y ）＝（x ＋2）（y ＋1），如果他所消费的商品x 和商品y 都增加⼀倍，那么商品x 和商品y 的边际替代率仍保持不变。

（）【答案】F【解析】边际替代率为：//u x MRS u y ??=-??当u （x ，y ）＝（x ＋2）（y ＋1）时，MRS ＝－（y ＋1）/（x ＋2）；当u （x ，y ）＝（2x ＋2）（2y ＋1）时，MRS ＝－2（2y ＋1）/[2（2x ＋2）]＝－（2y ＋1）/[2（x ＋1）]。

商品x 和商品y 的边际替代率发⽣变化。

2．在最优选择处，消费者的⽆差异曲线和预算线⼀定是相切的。

（）【答案】F【解析】最优选择处，⽆差异曲线和预算线可以相切，也可以不相切。

在凸性偏好和内部最优的条件下，相切是最优选择的充分条件，即相切处⼀定是最优选择，但最优选择不⼀定是相切的。

在边界最优的情况下，如商品完全替代的情况下，⽆差异曲线与预算线是相交的，⽽不是相切的。

3．已知⼀元钱的边际效⽤为5个单位，⼀⽀钢笔的边际效⽤为35个单位，则消费者需要⽤6元来买这⽀钢笔。

（）【答案】F 【解析】基数效⽤论中效⽤最⼤化条件为MU/P ＝λ，本题中35/6＞5，消费者需要7元来购买这⽀钢笔。

4．某消费者的效⽤函数为u （x ，y ）＝x ＋4y 1/2，商品x 的价格为1元/单位，商品y 的价格为2元/单位。

如果他的收⼊从100元增加到150元，他对商品y 的消费将增加超过10%，但少于50%。

（）【答案】F【解析】根据效⽤最⼤化的条件//x y P u x P u y= 可得：1/（2y －1/2）＝1/2，即y ＝1。

当收⼊变动时，消费者对y 的消费不变。

5．某消费者效⽤函数为u （x ，y ）＝max{x ，y}，如果商品x 的价格与商品y 的价格相等，该消费者会选择购买等量的x 和y 。

1 BUDGET CONSTRAINT1.A poor person who has an income of $1000 receives $100 worth offood stamps. Draw the budget constraint if the food stamp recipient can sell these coupons on the black market for less than their face value.2.Since 1979, recipients have been given food stamps. Before 1979,however, people bought food stamps at a subsidized rate. For example, to get $1 worth of food stamps, a household paid about 15￠(the exact amount varied by household characteristics and other factors). What is the budget constraint facing an individual if that individual may buy up to $100 per month in food stamps at 15￠per each $1 coupon. 3.During his first year at school, Ximing buys eight new collegetextbooks at a cost of $50 each. Used books cost $30 each. When the bookstore announces a 20% increase in new texts and a 10% increase in used texts next year, Ximing’s father offers him $80 extra. Is Ximing better off, the same, or worse off after the price change? Why?2 PREFERENCES1. Julia consumes cans of anchovies, A, and boxes of biscuits, B. Each ofher indifference curves reflects strictly diminishing marginal rates of substitution. Where A = 2 and B = 2, her marginal rate of substitution between cans of anchovies and boxes of biscuits equals -1. Will sheprefer a bundle with three cans of anchovies and a box of biscuits to a bundle with two of each? Why?2. What assumption or assumptions rule out the following phenomenon:Geoffrey has a bundle consisting of 6 apples and 8 raspberries. He states that if he is given 1 more apple, he will ask for 3 more raspberries to keep him indifferent between his old bundle and the new bundle that he will have after he receives the 1 additional apple.3. Draw indifference curves for the following people:a) John says: “I get no satisfaction from 1 ounce of vermouth or 3 ouncesof gin, but 1 ounce of vermouth and 3 ounces of gin (a martini) really turn me on.”b) Steve says: “I will not cut my hair to please my boss unless she paysme. My price is $300 plus $1 for every 1/8 inch of hair that is cut. In other words, for every $1 above $300 that the boss pays me, I will cut 1/8 inch off my hair.”c) In Part b of this problem, what is the marginal rate of substitutionbetween dollars and hair in the region below and above $300?d) Ann says: “I enjoy beer and pretzels, but after 12 beers, any additionalbeer makes me sick.”4. Jeffrey is five years old. He likes candy and hates spinach. He isallowed 2 candy bars a day, but his mother offers him 1 additional candy bar for every 2 ounce of spinach he eats.a) On these terms, Jeffrey eats 3 ounces of spinach and 3.5 candy barseach day. Using indifference curves, illustrate his optional choice.b) Suppose that Jeffrey’s mother does not give him 2 “free” candy barseach day but still gives him 1 candy bar for every 2 ounce of spinach he eats. Would his spinach consumption be greater or smaller than in Part a? Explain your answer.4 CHOICE1. Tara has a utility function U(B, Z) = ABαZβ, Where A, α, andβareconstraints, B is burritos, and Z is pizzas. If the price of burritos, p B is $2 and the price of pizzas, p Z is $1, what is Tara’s optimal bundle?2. Assume that there are two goods in the world: apples and raspberries.Say that Geoffrey has a utility function for these goods of the following type, where r denotes the quantity of raspberries and a the quantity if apples: U = r·a.a)Draw an indifference curve that is defined by this utility function andhas a utility level of 2500.b)What is the marginal rate of substitution between the raspberries andthe apples when Geoffrey consumes 50 raspberries and 50 apples?What is the marginal rate of substitution between these two goods when Geoffrey consumes 100 raspberries and 50 apples?c)If the price of raspberries is $1 per unit and the price of apples is $1per unit and Geoffrey has $100 to spend, what bundle of raspberries and apples will he buy? Is the marginal rate of substitution equal to the ratio of the prices of these goods in the optimal bundle? If not, why not?d)If the unit prices of the raspberries and the apples are $4 and $3,respectively, what bundle of raspberries and apples will Geoffrey buy with his income of $100?3. Steve’s utility function is U = BC, where B = veggie burgers per weekand C= packs of cigarettes per week. What is his marginal rate of substitution if veggie burgers are on the vertical axis and cigarettes are on the horizontal axis? Steve’s income is $120, the price of a veggie burger is $2, and that of a pack of cigarettes is $1. How many burgers and how many packs of cigarettes does Steve consume to maximize his utility? When a new tax raises the price of a burger to $3, what is his new optimal bundle? Illustrate your answers in a graph.5 DEMAND1.Roger’s utility function is U = B1/4Z3/4, his income is Y, the price of Bis p B, and the price of Z is p Z. Derive his demand curves.2.Derive Roger’s Engel curve for B for the utility given in problem 2.7 CONSUMER’S SUPPLUS1.If the inverse demand function is p = a–bQ, what is the consumersurplus if price is a/2?2.If the supply function is Q = Apη, what is the producer surplus if priceis p*?9 EQUILIBRIUM1.In 1998, a virus killed more than half the oysters used to producepearls in the world’s busiest undersea factory. Use a diagram to indicate why the price of pearls rose 18%. How did the equilibrium quantity change?2.Increasingly, instead of advertising in newspapers, individuals andfirms use Web sites that offer free classified ads, such as , , , and portals like Yahoo and America Online.Using a supply-and-demand model, explain what will happen to the equilibrium levels of newspaper advertising as the use of the Internet grows. Will the growth of the Internet affect the supply curve, the demand curve or both? Why?3.The U.S. supply of frozen orange juice comes from Florida and Brazil.What is the effect of a freeze that damages oranges in Florida on the price of frozen orange juice in the U.S. and on the quantities of orange juice sold by Floridian and Brazilian firms?4.The supply of corn by the U.S. is Q a= a + bp, and the supply by therest of the world is Q r = c + ep. What is the world supply?5. A rent control law limits the price of an apartment. What is the likelyeffect of such a law in the short run? What is the likely effect of the law in the long run? Be sure to discuss the quantity and quality of apartments available for rent.6.The government wants to drive the price of soybeans above theequilibrium price, p1 to p2. It offers growers a payment of x to reduce their output from Q1(the equilibrium level) to Q2, which is the quantity demanded by consumers at p2. How large must x be for growers to reduce output to this level? What are the effects of this program on consumers, farmers, and total welfare? Compare this approach to (a) offering a price support of p2, (b) offering a price support and a quota set at Q1, and (c) offering a price support and a quota set at Q2.10 TECHNOLOGY1.Michelle’s business produces ceramic cups using labor, clay, and akiln. She can manufacture 25 cups a day with one worker and 35 with two workers. Does her production process illustrate diminishing returns to scale or diminishing marginal returns to scale? What is the likely explanation for why output doesn’t increase proportionatelywith the number of workers?2. Suppose that the production function is q = L 3/4K 1/4.a. What is the average product of labor ，holding capital fixed at K ?b. What is the marginal product of labor?c. Does this production function have increasing, constant, or decreasing returns to scale?3. A good recipe for a French dish called ceviche requires 16 ounces of fillet of red snapper, 3 ounces of lime juice, 1 ounce of coriander, and 8 ounces of Bermuda onion. This combination of inputs is expressed in the following production function:1243min ,,,1638z z z y z ⎧⎫=⎨⎬⎩⎭ In this production function, z 1 is fillet of red snapper, z 2 is lime juice, z 3 is coriander, and z 4 is Bermuda onion. The unit of measure for each input is the ounce, and the unit of measure for ceviche (the output) is the quantity produced by the recipe. If a restaurant has on hand 32 ounces of snapper, 9 ounces of lime juice, 5 ounces of coriander, and 48 ounces of onion, how many “units ” of ceviche can it produce?4. Construct a total product curve for a function that exhibits diminishing marginal product throughout. Then construct another total product curve for a function that exhibits initially constant and subsequently diminishing marginal product. Below the graphs of these two total products curve, derive the corresponding average and marginalfunctions. Check to see that the curves you have drawn are consistent with what you know about the relationship between the average and marginal product curves.11 PROFIT MAXIMIZATION1.You have 60 minutes to take an exam with two questions. You want tomaximize your score. Toward the end of the exam, the more time you spend on either question, the fewer extra points per minutes you get for that question. How should you allocate time between the two questions?(Hint: Think about producing an output of a score on the exam using inputs of time spent on each of the problem)2. A competitive firm’s production function is y = L + 2LK + K. What isits marginal revenue product of labor?3.A firm’s production function is y = ALαKβ. What is the firm’s marginalrevenue product of labor?1L2, 4.A competitive firm has the production of function Q= 20L–4 where Q is the number of units of output produced and L is the number of units of labor (the only input) used. The output price is $2, the wage rate is $1, and the firm faces a fixed cost of $100.a)What is the profit-maximizing quantity of labor demanded by thefirm?b)What is the firm’s profit in the short run?c)If, in the long run, the output price changes so that profits are zero,what is the quantity of labor demanded in the long run?5.A competitive firm has the production function. Q = LαKβ, where Q isthe number of units of output produced, L is the number of units of labor used, and K is the number of units of capital used. The output price p, the wage rate w, and the cost of capital r are given. Assume that α > 0, β > 0, and 0 < ( α + β ) < 1.a)What is the firm’s profit-maximizing quantity of labor if the quantityof capital is fixed at K?b)What is the firm’s profit-maximizing level of capital if both capitaland labor are variable? (Hint: Use the profit-maximizing capital-labor ratio K/L to substitute for the level of labor.)12 COST MINIMIZATION1.Assume that a firm produces 90 units of output using 9 units of inputX and 9 units of input Y. The f irm’s technological possibilities can be represented by the production function Q = 10X1/2Y1/2.a)If the price of X is $8 and the price of Y is $16, is the inputcombination of 9 units of X and 9 units of Y the most efficient way to produce 90 units of output?b)What must the ratio of input prices be for this input combination to beefficient?c)Assume that the price of X is $1 and the price of Y is $2. Derive theleast-cost way to produce 400 units of output.2.A medical center produces health services using two inputs: hospitalbeds and labor. There is a government regulation restricting the number of beds to B. Assume that the medical center is currently usingB beds and L units of labor to produce Q1 units of health services. Alsoassume that the medical center plans to expand its output to Q2 units of health services. Prepare a diagram to show how this government regulation restricting the number of hospital beds would affect the efficiency of delivering health services.3.A trucking firm’s output is measured by the number m of truck-milesmoved per day. The firm’s operating costs are as follows:i.wages of trucks, $w per hourii.cost of gasoline, $p per galloniii.fuel consumption, g= A+ Bs, where g is gallons of gasoline per truck-mile, s is the speed at which a truck is driven, and A and B are constantsa)Derive the total variable cost function of the firm if it has an unlimitednumber of trucks.b)What does the cost function look like if the firm has only one truckand that truck can be driven for a maximum of ten hours per day?4.A college student is considering whether to operate a lawn-mowingbusiness for the summer or work in a business owned by her family.Her time is worth $w1 per hour and she can work as many hours as she chooses in the family business at this rate. If she starts her own business, she will have to buy gasoline for her lawn mower at a price of $w2 per gallon. She can rent a small mower for $w3 per hour. The mower cuts a 12-inch swath of lawn and uses 1/3 gallon of gasoline per hour. With this mower, she can cut 10,000 square feet of lawn in an hour. (Use 10,000 square feet as the units of measurement for output.) Our college student can rent a large mower for $w4 per hour.This mower uses 1 gallon of gasoline per hour and cuts 3 units of lawn per hour.a)Verify that the production function for the two mowers are as follows:y = min{z1, 3z2, z3}y = 3min{z1, z2, z4}Assume that z1 is hours of labor, z2 is gallons of gasoline, and z3 and z4are the hours of the small mower and the large mower, respectively.b)Derive the cost functions.c)Show that using the small mower is a cheaper way to cut grass if 2w1 <w4 – 3w3. Why is this result independent of the price of gasoline?d)How high a price must our college student receive for cutting a unit oflawn in order to induce her to set up her own lawn-mowing firm ratherthan work in the family business?e)Assume that a firm uses two types of input in the production of acertain commodity. What is the maximum output if the marginal product of input is MP1 = 100X2 –X1 and the marginal product of input2 is MP2 = 100X1 –X2, the total amount that can be spent on inputs is$1,000, the price of input 1 is $2, and the price of 2 is $5?13 COST CURVES1.The only variable input a janitorial service firm uses to clean offices isworkers who are paid a wage, w, of $8 an hour. Each worker can clean four offices in an hour. Use math to determine the variable cost, the average variable cost, and the marginal cost of cleaning one more office. Draw a diagram to show the average cost, and marginal cost curves.2.Gail works in a flower shop, where she produces 10 floralarrangements per hour. She is paid $10 an hour for the first eight hours she works and $15 an hour for each additional hour she works. What is the firm’s cost function? What are its AC, AVC, and MC functions?Draw the AC, AVC, and MC curves.3.A firm has two plants that produce identical output. The cost functionsare C1 = 10y– 4y2 + y3and C2 = 10y– 2y2 + y3.b.At what output levels does the average cost curve of each plant reachits minimum?c. If the firm wants to produce 4 units of output, how much should it produce in each plant?4. A firm that makes widgets must build a plan that will cost $10,000. The plant will be able to produce up to 10,000 units, at which point its capacity will be reached and a new plant will be needed. The total cost function for each plant (including the fixed cost of building the plant) is C (y ) = 10,000 – x 1/2/100.a) Determine the cost function for this firm.b) Is this cost function subadditive over the range of outputs from 1 unit to 10,000 units? Is it subadditive for all levels of output?14 FIRM SUPPLY1. If a competitive firm ’s cost function is C (y ) = 100 + 10y – y 2 + 31y 3, what is the firm ’s marginal cost function? What is the firm ’s profit- maximizing condition?2. If a competitive firm ’s cost function is C (y ) = a + by + cy 2 + dy 3, where a , b , c , and d are constants, what is the firm ’s marginal cost function? What is the firm ’s profit-maximizing condition?3. Consider a firm with a total cost curve of TC = 1,000 + q 3/3 – 2q 2 + 6q . a) What is the lowest price at which this firm will want to supply a positive amount to the market in the short run?b) At the “lowest price”, how much will be supplied?c) How much will be supplied in the short run if the price is $10?4. What is the effect on firm and market equilibrium of a law requiring afirm to give its workers six months’ notice before it can shut down its plant?15 INDUSTRY SUPPLY1. Each firm in a competitive market has a cost function of C = 16 + y2.The market demand function is Q = 24–y. Determine the equilibrium price, quantity per firm, market quantity, and number of firms.2. Assume that the taxi industry in the town of New City is perfectlycompetitive. Also assume that the constant marginal cost of a taxi ride is $5 per trip and that each taxi is capable of making 20 trips a day. We will let the demand function for taxi rides each day be D(p) = 1,100 –20p.a)What is the perfectly competitive price of a taxi ride?b)How many rides will the citizens of New City make every day?c)How many taxis will operate in New City?Assume that every taxi that operates in New City has a special license. Therefore, the number of such licenses is the same as the number of taxis that you calculated in Part c of this problem. Further assume that the demand for taxi rides has increased and is now D(p) =1,200 - 20p. The cost of operating a taxi is still $5 per ride, and the number of taxis has not changed.d)Calculate the price that will equate demand with supply.e)Calculate the profit that each taxi will earn on a ride.f)Calculate the daily profit of each taxi. (Hint: Continue to assume thateach taxi can make only 20 rides a day)3. A competitive market has an unlimited number of potential suppliersproducing the same output, and each supplier has a long-run average cost function of AC= q2 –4q+ 6 and a long-run marginal cost function of MC = 3q2 – 8q + 6.a) Find the equilibrium quantity q produced by each firm in the long run.b) Find the long-run equilibrium price.4. Assume that a very large number of firms in an industry all have accessto the same production technology. The total cost function associated with this technology is TC(Q) = 40Q–24Q2 + 4Q3. If the demand function for the industry’s product is Q = 19 –P, how many firms will produce positive amounts of output at a competitive (that is, zero profit) equilibrium?5. Assume that a certain small town contains a large number ofwidget-producing firms. All the firms buy oil from the same refinery.Firm 1 is situated very close to the refinery, and the other firms are located 50 miles away. Firm 1 pays $18 per barrel for the oil, while theother firms pay $18 per barrel plus a transportation charge of $.05 cents a mile, or a total of $20.50 per barrel.To produce four widgets, a firm needs 1/10 barrel of oil, 1/2 hour of labor, and the use of one machine. The cost of labor is $10 per hour, and the necessary machine can be rented for $5 per hour. No firm has the capacity to produce more than 100 units of widgets.a)Derive the supply curve for firm1. Derive the supply curve for all theother firms.b)What is the equilibrium price?c)Does any firm earn economic rent (that is, extra economic profit) inthe industry?d)Does firm 1 affect the price of widgets in the industry? If not, whynot?e)Suppose that there is no capacity limit. What will the equilibrium pricebe?f)Will firm 1 affect the price when there is unlimited capacity?16 MONOPOLY1.Show that after a shift in the demand curve, a monopoly’s price mayremain constant but its output may rise.2.When is a monopoly unlikely to be profitable?(Hint: Discuss therelationship between market demand and average cost)3.The inverse demand curve a monopoly faces is p = 100 - Q. The firm’scost curve is C(Q) = 10 + 5Q. What is the profit-maximizing solution?4.How does your answer to Problem 3 change if C(Q) = 100 + 5Q?5.A monopoly’s production function is: y = L1/2K1/2, where L is labor andK is capital. The demand function is p = 100–y. The wage, w, is $1 per hour, and the rental cost of capital, r, is $4.a.Derive the long-run total cost curve equation as a function of y.b.What quantity maximizes this firm’s profit?c.Find the optimal input combination that produces the profit-maximizing quantity. Illustrate with a graph.6. Suppose that a monopolist faces a demand curve of P = 100 - 2Q. Herfirm has costs of C(Q) = 5Q2.a) What is the revenue function for this monopolist?b) What is the marginal revenue function?c) What is the marginal cost function?d) What is the profit-maximizing output for this monopolist?e) What is the maximum profit this firm can make?f) If this monopolist has to pay a permission free of $150 to the stategovernment in order to start the business, will her optimal level of output change? If not, why not?17 FACTOR MARKETS1.A monopsony faces a supply curve: w = 10 + x. What is its marginalexpenditure curve?18 OLIGOPOLY1.What is the duopoly Cournot equilibrium if the market demandfunction is Q = 1000–1000p, and each firm’s marginal cost is $0.28 per unit?2. Consider a duopolistic market with two firms, A and B, facing ademand curve of p = 1 –q A–q B. Assume that initially each firm has access to the same technology with constant returns to scale and that the cost of production is C A = q A/2 for firm A and C B= q B/2 for firm B.a) What is the profit function for each firm?b) Graph the reaction functions for firms.c) What is the equilibrium outputs?d) Assume that the initial output levels of the two firms are given by pointX(3/10, 4/10) and Y(1/10, 2/10). Show in a graph the process of change in the output levels of the two firms and the point at which their output levels converge.3. A duopoly faces a market demand of p= 120–Q. Firm 1 has aconstant marginal cost of MC1 = 20. Firm 2’s constant marginal cost is MC2 = 40. Calculate the output of each firm, market output, and price if there is (a) a collusive equilibrium or (b) a Cournot equilibrium.4. Assume that there are two firms in a market, firm 1 and firm 2. Thetotal demand for the identical product they make is p = 200 – 2(q1 + q2), where q1 is the output of firm 1 and q2 is the output of firm 2. The production costs of firm 1 and firm 2 are C1 = q12and C2 = q22, respectively.a) Assume that firm 2 decides to produce either 20, 40, 60, or 100 units ofoutput. Show the demand curve and the marginal revenue curve facing firm 1 in each of these situations, assuming that the output levels will remain unchanged once they are chosen.b) Define the output that represents the best (the profit-maximizing)response of firm 1 to each of the output levels chosen by firm 2.19 EXCHANGE1.Initially, Michael has 10 candy bars and 5 cookies, and Tony has 5candy bars and 10 cookies. After trading, Michael has 12 candy bars and 3 cookies. In an Edgeworth box, label the initial Allocation A and the new Allocation B. Draw some indifference curves that are consistent with this trade being optimal for both Michael and Tony. 2.In a pure exchange economy with two goods, G and H, the two tradershave Cobb-Douglas utility functions. Amos’s utility is U a =(G a)α(H a)1-α, and Elise’s is U e = (G e)β(H e) 1-β, what are their marginalrates of substitution?3. Continuing with problem 3: between them, Amos and Elise own 100 units of G and 50 units of H . Thus if Amos has G a and H a , Elise has G e =100 – G a and H e = 50 – H a . Solve for their contract curve.4. Arnold and Brigitte are marooned on a deserted island. Arnold has exactly one unit of Xylose and Brigitte has exactly one unit of Yam. Their preferences between these two items are represented by the following two equations:1/32/31/21/2A A AB B B U X Y U X Y =⋅=⋅In these equations, X A and Y A are the consumption of Xylose and Yam by Arnold. Similarly, X B and Y B are the consumption of Xylose and Yam by Brigitte.a) Is the following allocation Pareto-optimal? Explain why or why not.1211,,,2323A AB B X Y andX Y ==== b) If Arnold and Brigitte were to trade between themselves, would they be able to attain this allocation as a competitive equilibrium? What would be the equilibrium price ratio of Xylose to Yam? Would Arnold and Brigitte be able to afford this allocation at the equilibrium prices, given their endowments? If not, what kind of income transfer would be necessary?5. Two people trade two goods that they cannot produce. Suppose that one consumer ’s indifference curves are bowed away from the origin – the usual type of curves – but the other ’s are concave to the origin.In an Edgeworth box, show that a point of tangency between the two consumers’indifference curves is not a Pareto-efficient bundle.(Identify another allocation that Pareto dominates.)6.The demands for two goods depend on the prices of Good 1 and Good2, p1 and p2, Q1 = 15 – 3p1 + p2, Q2 = 6 – 2p2 + p1, but each supply curve depends on only its own price: Q1 = 2 + p1, Q2 = 1 + p2. Solve for the equilibrium: p 1, p2, Q1, and Q2.20 PRODUCTION1. Assume that you have exactly 100 hours of labor to allocate betweenproducing good X and good Y. Your output of goods X and Y depends solely on the hours of labor you spend in the following way:X=and Y=a)If you can sell your output of goods X and Y at the fixed prices P X = 10and P Y= 5, how much of goods X and Y would you produce to maximize your profits?b)Now assume further that you have the following utility function:U=If you can trade a bundle of goods X and Y that you produce in the market at fixed prices of P X = 10 and P Y = 5, what bundle would you produce and what bundle would you consume to maximize your utility?Are you a net demander and a net supplier of the two goods? Draw adiagram to depict what is happening.2. Suppose that the production possibilities frontier for cheeseburgers (C)and milk-shakers (M) is given by C + 2M = 600.a) Graph this function.b) Assuming that people prefer to eat two cheeseburgers with everymilk-shaker, how much of each product will be produced? Indicate this point in your graph.c) Assuming that this fast-food economy is operating efficiently, whatprice ratio (P C/P M) will prevail?21 WELFARE1. Suppose that society used the “opposite”of a Rawlsian welfarefunction: it tried to maximize the well-being of the best-off member of society. Write this welfare function. What allocation maximizes welfare in this society?2. Assume that Bob has a utility function of U = 8X1 + 1X2 – 3X3 and Joanhas a utility function of U = –2X1 + 7X2 + 5X3. Consider the following allocation:a)Is this allocation envy free?b)Is this allocation Pareto-optimal?c)Find a Pareto-optimal allocation, and determine whether it is envyfree.d)Do you think that the allocation in Part c of this problem is desirable?Why or why not?22 EXTERNALITIES1.Suppose that the only way to reduce pollution from paper productionis to reduce output. The government imposes a tax equal to the marginal harm from the pollution on the monopoly producer. Show that the tax may raise welfare.2.Suppose that the inverse demand curve for paper is p = 200–y, theprivate marginal cost (unregulated competitive market supply) is MC p = 80 + Q, and the marginal harm from gunk is MC g = y.a.What is the unregulated competitive equilibrium?b.What is the social optimum? What specific tax (per unit of output orgunk) results in the social optimum?c.What is the unregulated monopoly equilibrium?d.How would you optimally regulate the monopoly? What is theresulting equilibrium?3. A soot-spewing factory that produces steel windows is next to a。

Chapter 2 Budget ConstraintIntermediate Microeconomics:A Modern Approach （7th Edition）By Hal R. Varian (University of California at Berkeley)第2章：预算约束（含习题详细解答）中级微观经济学：现代方法(第七版)范里安著（加州大学伯克利）曹乾译（东南大学）caoqianseu@2 预算约束消费者的经济理论很简单:消费者们选择他们能够买得起的最佳的商品组合。

为了说明该理论,需要更准确地阐述上句中 “最佳”以及 “能够买得起”的含义。

本章将阐述如何描述消费者能够买得起;下一章则重点分析消费者如何确定什么为最佳。

这样我们就可以详细研究消费者行为这一简单模型的意义。

2.1预算约束我们从预算约束．．．．(budget constraint)的概念入手分析。

假设消费者可从某组商品中进行选择。

在现实生活中有许多商品可供选择,但根据我们的目的,考虑两种商品的情形很方便,因为我们可以借助图形刻画消费者的选择。

我们将消费者的消费束．．．(consumption bundle)用),(21x x 表示。

),(21x x 是一个有序数对,它表明消费者选择消费商品1的数量即1x ,商品2的数量即2x 。

有时用单个符号X 来表示消费束更方便, X 为),(21x x 的缩写。

假设两种商品的价格),(21p p 以及消费者必须花费的金钱数m 均为可知,则消费者的预算约束可以写为m x p x p ≤+2211 (2。

1)其中: 11x p 是消费者花费在商品1上的金钱数, 22x p 是消费者花费在商品2上的金钱数。

消费者的预算约束要求花费在两种商品上的金钱总数不超过消费者必须花费的钱数。

消费者可以买得起的消费束是指那些花费不超过m 的消费束。

我们把在价格),(21p p 和收入m 下可以买得起的消费束称为消费者的预算集．．．(budget set)。

Chapter1NAMEThe MarketIntroduction.The problems in this chapter examine some variations on the apartment market described in the text.In most of the problems we work with the true demand curve constructed from the reservation prices of the consumers rather than the“smoothed”demand curve that we used in the text.Remember that the reservation price of a consumer is that price where he is just indifferent between renting or not renting the apartment. At anyprice below the reservation price the consumer will demand one apartment,at anyprice above the reservation price the consumer will de-mand zero apartments,and exactlyat the reservation price the consumer will be indifferent between having zero or one apartment.You should also observe that when demand curves have the“stair-case”shape used here,there will typically be a range of prices where supplyequals demand.Thus we will ask for the the highest and lowest price in the range.1.1(3)Suppose that we have8people who want to rent an apartment. Their reservation prices are given below.(To keep the numbers small, think of these numbers as being dailyrent pay ments.)Person=A B C D E F G HPrice=402530351018155(a)Plot the market demand curve in the following graph.(Hint:When the market price is equal to some consumer i’s reservation price,there will be two different quantities of apartments demanded,since consumer i will be indifferent between having or not having an apartment.)2THE MARKET(Ch.1)012345678102030406050PriceApartments(b)Suppose the supplyof apartments isfixed at5units.In this case there is a whole range of prices that will be equilibrium prices.What is the highest price that would make the demand for apartments equal to5 units?$18.(c)What is the lowest price that would make the market demand equal to5units?$15.(d)With a supplyof4apartments,which of the people A–H end up getting apartments?A,B,C,D.(e)What if the supplyof apartments increases to6units.What is the range of equilibrium prices?$10to$15.1.2(3)Suppose that there are originally5units in the market and that 1of them is turned into a condominium.(a)Suppose that person A decides to buythe condominium.What will be the highest price at which the demand for apartments will equal the supplyof apartments?What will be the lowest price?Enter y our an-swers in column A,in the table.Then calculate the equilibrium prices of apartments if B,C,...,decide to buythe condominium.NAME3Person A B C D E F G H High price1818181825252525 Low price1515151518151818 (b)Suppose that there were two people at each reservation price and10 apartments.What is the highest price at which demand equals supply?18.Suppose that one of the apartments was turned into a condo-minium.Is that price still an equilibrium price?Yes.1.3(2)Suppose now that a monopolist owns all the apartments and thathe is trying to determine which price and quantity maximize his revenues.(a)Fill in the box with the maximum price and revenue that the monop-olist can make if he rents1,2,...,8apartments.(Assume that he must charge one price for all apartments.)Number12345678 Price403530251815105 Revenue40709010090907040(b)Which of the people A–F would get apartments?A,B,C,D.(c)If the monopolist were required bylaw to rent exactly5apartments, what price would he charge to maximize his revenue?$18.(d)Who would get apartments?A,B,C,D,F.(e)If this landlord could charge each individual a different price,and heknew the reservation prices of all the individuals,what is the maximum revenue he could make if he rented all5apartments?$148.(f)If5apartments were rented,which individuals would get the apart-ments?A,B,C,D,F.1.4(2)Suppose that there are5apartments to be rented and that the cityrent-control board sets a maximum rent of$9.Further suppose that people A,B,C,D,and E manage to get an apartment,while F,G,andH are frozen out.4THE MARKET(Ch.1)(a)If subletting is legal—or,at least,practiced—who will sublet to whomin equilibrium?(Assume that people who sublet can evade the cityrent-control restrictions.)E,who is willing to payonly$10for an apartment would sublet to F,who is willing to pay$18.(b)What will be the maximum amount that can be charged for the sublet payment?$18.(c)If you have rent control with unlimited subletting allowed,which ofthe consumers described above will end up in the5apartments?A,B,C,D,F.(d)How does this compare to the market outcome?It’s the same.1.5(2)In the text we argued that a tax on landlords would not getpassed along to the renters.What would happen if instead the tax wasimposed on renters?(a)To answer this question,consider the group of people in Problem1.1.What is the maximum that theywould be willing to payto the landlordif theyeach had to paya$5tax on apartments to the city?Fill in thebox below with these reservation prices.Person A B C D E F G H Reservation Price35202530513100 (b)Using this information determine the maximum equilibrium price ifthere are5apartments to be rented.$13.(c)Of course,the total price a renter pays consists of his or her rent plusthe tax.This amount is$18.(d)How does this compare to what happens if the tax is levied on the landlords?It’s the same.Chapter 2NAMEBudget ConstraintIntroduction.These workouts are designed to build your skills in de-scribing economic situations with graphs and algebra.Budget sets are a good place to start,because both the algebra and the graphing are very easy.Where there are just two goods,a consumer who consumes x 1units of good 1and x 2units of good 2is said to consume the consumption bun-dle ,(x 1,x 2).Anyconsumption bundle can be represented bya point on a two-dimensional graph with quantities of good 1on the horizontal axis and quantities of good 2on the vertical axis.If the prices are p 1for good 1and p 2for good 2,and if the consumer has income m ,then she can afford anyconsumption bundle,(x 1,x 2),such that p 1x 1+p 2x 2≤m .On a graph,the budget line is just the line segment with equation p 1x 1+p 2x 2=m and with x 1and x 2both nonnegative.The budget line is the boundary of the budget set .All of the points that the consumer can afford lie on one side of the line and all of the points that the consumer cannot afford lie on the other.If you know prices and income,you can construct a consumer’s bud-get line byfinding two commoditybundles that she can “just afford”and drawing the straight line that runs through both points.Example:Myrtle has 50dollars to spend.She consumes only apples and bananas.Apples cost 2dollars each and bananas cost 1dollar each.You are to graph her budget line,where apples are measured on the horizontal axis and bananas on the vertical axis.Notice that if she spends all of her income on apples,she can afford 25apples and no bananas.Therefore her budget line goes through the point (25,0)on the horizontal axis.If she spends all of her income on bananas,she can afford 50bananas and no apples.Therfore her budget line also passes throught the point (0,50)on the vertical axis.Mark these two points on your graph.Then draw a straight line between them.This is Myrtle’s budget line.What if you are not told prices or income,but you know two com-moditybundles that the consumer can just afford?Then,if there are just two commodities,you know that a unique line can be drawn through two points,so you have enough information to draw the budget line.Example:Laurel consumes onlyale and bread.If she spends all of her income,she can just afford 20bottles of ale and 5loaves of bread.Another commoditybundle that she can afford if she spends her entire income is 10bottles of ale and 10loaves of bread.If the price of ale is 1dollar per bottle,how much moneydoes she have to spend?You could solve this problem graphically.Measure ale on the horizontal axis and bread on the vertical axis.Plot the two points,(20,5)and (10,10),that you know to be on the budget line.Draw the straight line between these points and extend the line to the horizontal axis.This point denotes the amount of6BUDGET CONSTRAINT (Ch.2)ale Laurel can afford if she spends all of her moneyon ale.Since ale costs 1dollar a bottle,her income in dollars is equal to the largest number of bottles she can afford.Alternatively,you can reason as follows.Since the bundles (20,5)and (10,10)cost the same,it must be that giving up 10bottles of ale makes her able to afford an extra 5loaves of bread.So bread costs twice as much as ale.The price of ale is 1dollar,so the price of bread is 2dollars.The bundle (20,5)costs as much as her income.Therefore her income must be 20×1+5×2=30.When you have completed this workout,we hope that you will be able to do the following:•Write an equation for the budget line and draw the budget set on a graph when you are given prices and income or when you are given two points on the budget line.•Graph the effects of changes in prices and income on budget sets.•Understand the concept of numeraire and know what happens to the budget set when income and all prices are multiplied bythe same positive amount.•Know what the budget set looks like if one or more of the prices is negative.•See that the idea of a “budget set”can be applied to constrained choices where there are other constraints on what you can have,in addition to a constraint on moneyexpenditure.NAME 72.1(0)You have an income of $40to spend on two -modity1costs $10per unit,and commodity2costs $5per unit.(a)Write down your budget equation.10x 1+5x 2=40.(b)If you spent all your income on commodity 1,how much could you buy?4.(c)If you spent all of your income on commodity 2,how much could you buy?8.Use blue ink to draw your budget line in the graphbelow.02468246x1x28(d)Suppose that the price of commodity1falls to $5while every thing else stays the same.Write down your new budget equation.5x 1+5x 2=40.On the graph above,use red ink to draw your new budget line.(e)Suppose that the amount you are allowed to spend falls to $30,while the prices of both commodities remain at $5.Write down your budget equation.5x 1+5x 2=30.Use black ink to draw this budget line.(f)On your diagram,use blue ink to shade in the area representing com-moditybundles that y ou can afford with the budget in Part (e)but could not afford to buywith the budget in Part (a).Use black ink or pencil to shade in the area representing commoditybundles that y ou could afford with the budget in Part (a)but cannot afford with the budget in Part (e).2.2(0)On the graph below,draw a budget line for each case.8BUDGET CONSTRAINT (Ch.2)(a)p 1=1,p 2=1,m =15.(Use blue ink.)(b)p 1=1,p 2=2,m =20.(Use red ink.)(c)p 1=0,p 2=1,m =10.(Use black ink.)(d)p 1=p 2,m =15p 1.(Use pencil or black ink.Hint:How much of good 1couldyou afford if you spend your entire budget on good 1?)0510152051015x1x2202.3(0)Your budget is such that if you spend your entire income,youcan afford either 4units of good x and 6units of good y or 12units of x and 2units of y .(a)Mark these two consumption bundles and draw the budget line in the graph below.04812164812xy 16(b)What is the ratio of the price of x to the price of y ?1/2.(c)If you spent all of your income on x ,how much x could you buy?16.(d)If you spent all of your income on y ,how much y could you buy?8.(e)Write a budget equation that gives you this budget line,where the price of x is 1.x +2y =16.(f)Write another budget equation that gives you the same budget line,but where the price of x is 3.3x +6y =48.2.4(1)Murphywas consuming 100units of X and 50units of Y .Theprice of X rose from 2to 3.The price of Y remained at 4.(a)How much would Murphy’s income have to rise so that he can still exactlyafford 100units of X and 50units of Y ?$100.2.5(1)If Amyspent her entire allowance,she could afford 8candybars and 8comic books a week.She could also just afford 10candybars and 4comic books a week.The price of a candybar is 50cents.Draw her budget line in the box below.What is Amy’s weekly allowance?$6.0816243281624Candy barsComic books3212 2.6(0)In a small countrynear the Baltic Sea,there are onlythree commodities:potatoes,meatballs,and jam.Prices have been remark-ablystable for the last 50y ears or so.Potatoes cost 2crowns per sack,meatballs cost 4crowns per crock,and jam costs 6crowns per jar.(a)Write down a budget equation for a citizen named Gunnar who has an income of 360crowns per year.Let P stand for the number of sacks of potatoes,M for the number of crocks of meatballs,and J for the number of jars of jam consumed byGunnar in a y ear.2P +4M +6J =360.(b)The citizens of this countryare in general veryclever people,but they are not good at multiplying by 2.This made shopping for potatoes excru-ciatinglydifficult for manycitizens.Therefore it was decided to introduce a new unit of currency,such that potatoes would be the numeraire.A sack of potatoes costs one unit of the new currencywhile the same rel-ative prices applyas in the past.In terms of the new currency ,what is the price of meatballs?2crowns.(c)In terms of the new currency,what is the price of jam?3crowns.(d)What would Gunnar’s income in the new currencyhave to be for him to be exactlyable to afford the same commoditybundles that he could afford before the change?180crowns.(e)Write down Gunnar’s new budget equation.P +2M +3J =180.Is Gunnar’s budget set anydifferent than it was before the change?No.2.7(0)Edmund Stench consumes two commodities,namelygarbage and punk rock video cassettes.He doesn’t actuallyeat the former but keeps it in his backy ard where it is eaten bybillygoats and assorted vermin.The reason that he accepts the garbage is that people payhim $2per sack for taking it.Edmund can accept as much garbage as he wishes at that price.He has no other source of income.Video cassettes cost him $6each.(a)If Edmund accepts zero sacks of garbage,how manyvideo cassettescan he buy?0.NAME 11(b)If he accepts 15sacks of garbage,how manyvideo cassettes can he buy?5.(c)Write down an equation for his budget line.6C −2G =0.(d)Draw Edmund’s budget line and shade in his budget set.0510152051015Video cassettesGarbage 202.8(0)If you think Edmund is odd,consider his brother Emmett.Emmett consumes speeches bypoliticians and universityadministrators.He is paid $1per hour for listening to politicians and $2per hour for listening to universityadministrators.(Emmett is in great demand to help fill emptychairs at public lectures because of his distinguished appearance and his abilityto refrain from making rude noises.)Emmett consumes one good for which he must pay.We have agreed not to disclose what that good is,but we can tell you that it costs $15per unit and we shall call it Good X .In additionto what he is paid for consuming speeches,Emmett receives a pension of $50per week.0255075100255075Politician speechesAdministrator speeches10012BUDGET CONSTRAINT (Ch.2)(a)Write down a budget equation stating those combinations of the three commodities,Good X ,hours of speeches bypoliticians (P ),and hours of speeches byuniversityadministrators (A )that Emmett could afford to consume per week.15X −1P −2A =50.(b)On the graph above,draw a two-dimensional diagram showing the locus of consumptions of the two kinds of speeches that would be possible for Emmett if he consumed 10units of Good X per week.2.9(0)Jonathan Livingstone Yuppie is a prosperous lawyer.He has,in his own words,“outgrown those confining two-commoditylim-its.”Jonathan consumes three goods,unblended Scotch whiskey,de-signer tennis shoes,and meals in French gourmet restaurants.The price of Jonathan’s brand of whiskeyis $20per bottle,the price of designer tennis shoes is $80per pair,and the price of gourmet restaurant meals is $50per meal.After he has paid his taxes and alimony,Jonathan has $400a week to spend.(a)Write down a budget equation for Jonathan,where W stands for the number of bottles of whiskey,T stands for the number of pairs of tennis shoes,and M for the number of gourmet restaurant meals that he consumes.20W +80T +50M =400.(b)Draw a three-dimensional diagram to show his budget bel the intersections of the budget set with each axis.(c)Suppose that he determines that he will buyone pair of designer tennis shoes per week.What equation must be satisfied bythe combinations of restaurant meals and whiskeythat he could afford?20W +50M =320.2.10(0)Martha is preparing for exams in economics and sociology.She has time to read 40pages of economics and 30pages of sociology.In the same amount of time she could also read 30pages of economics and 60pages of sociology.(a)Assuming that the number of pages per hour that she can read of either subject does not depend on how she allocates her time,how many pages of sociologycould she read if she decided to spend all of her time on sociologyand none on economics?150pages.(Hint:You have two points on her budget line,so you should be able to determine the entire line.)(b)How manypages of economics could she read if she decided to spend all of her time reading economics?50pages.2.11(1)HarryHy pe has $5,000to spend on advertising a new kind ofdehydrated sushi.Market research shows that the people most likely to buythis new product are recent recipients of M.B.A.degrees and lawy ers who own hot tubs.Harryis considering advertising in two publications,a boring business magazine and a trendyconsumer publication for people who wish theylived in California.Fact 1:Ads in the boring business magazine cost $500each and ads in the consumer magazine cost $250each.Fact 2:Each ad in the business magazine will be read by1,000recent M.B.A.’s and 300lawyers with hot tubs.Fact 3:Each ad in the consumer publication will be read by300recent M.B.A.’s and 250lawyers who own hot tubs.Fact 4:Nobodyreads more than one ad,and nobodywho reads one magazine reads the other.(a)If Harryspends his entire advertising budget on the business pub-lication,his ad will be read by10,000recent M.B.A.’s and by3,000lawyers with hot tubs.(b)If he spends his entire advertising budget on the consumer publication,his ad will be read by 6,000recent M.B.A.’s and by5,000lawyers with hot tubs.(c)Suppose he spent half of his advertising budget on each publication.His ad would be read by 8,000recent M.B.A.’s and by4,000lawyers with hot tubs.(d)Draw a “budget line”showing the combinations of number of readings byrecent M.B.A.’s and bylawy ers with hot tubs that he can obtain if he spends his entire advertising budget.Does this line extend all the way to the axes?No.Sketch,shade in,and label the budget set,which includes all the combinations of MBA’s and lawyers he can reach if he spends no more than his budget.(e)Let M stand for the number of instances of an ad being read byan M.B.A.and L stand for the number of instances of an ad being read by a lawyer.This budget line is a line segment that lies on the line with equation M +2L =16.With a fixed advertising budget,how manyreadings byM.B.A.’s must he sacrifice to get an additional reading bya lawy er with a hot tub?2.04812164812Lawyers x 1000MBA's x 10001610262.12(0)On the planet Mungo,theyhave two kinds of money ,blue moneyand red money .Everycommodityhas two prices—a red-money price and a blue-moneyprice.EveryMungoan has two incomes—a red income and a blue income.In order to buyan object,a Mungoan has to paythat object’s red-moneyprice in red moneyand its blue-moneyprice in blue money .(The shops simplyhave two cash registers,and y ou have to payat both registers to buyan object.)It is forbidden to trade one kind of moneyfor the other,and this prohibition is strictlyenforced byMungo’s ruthless and efficient monetarypolice.•There are just two consumer goods on Mungo,ambrosia and bubble gum.All Mungoans prefer more of each good to less.•The blue prices are 1bcu (bcu stands for blue currencyunit)per unit of ambrosia and 1bcu per unit of bubble gum.•The red prices are 2rcus (red currencyunits)per unit of ambrosia and 6rcus per unit of bubble gum.(a)On the graph below,draw the red budget (with red ink)and the blue budget (with blue ink)for a Mungoan named Harold whose blue income is 10and whose red income is 30.Shade in the “budget set”containing all of the commoditybundles that Harold can afford,givenNAME 15its ∗two budget constraints.Remember,Harold has to have enough blue money and enough red moneyto payboth the blue-moneycost and the red-moneycost of a bundle ofgoods.0510152051015AmbrosiaGum 20(b)Another Mungoan,Gladys,faces the same prices that Harold faces and has the same red income as Harold,but Gladys has a blue income of 20.Explain how it is that Gladys will not spend its entire blue income no matter what its tastes maybe.(Hint Draw Glady s’s budget lines.)The blue budget line lies strictlyoutside the red budget line,so to satisfyboth budgets,one must be strictlyinside the red budget line.(c)A group of radical economic reformers on Mungo believe that the currencyrules are unfair.“Whyshould every one have to paytwo prices for every thing?”theyask.Theypropose the following scheme.Mungo will continue to have two currencies,everygood will have a blue price and a red price,and everyMungoan will have a blue income and a red income.But nobodyhas to payboth prices.Instead,every one on Mungo must declare itself to be either a Blue-MoneyPurchaser (a “Blue”)or a Red-Money Purchaser (a “Red”)before it buys anything at all.Blues must make all of their purchases in blue moneyat the blue prices,spending onlytheir blue incomes.Reds must make all of their purchases in red money,spending only their red incomes.Suppose that Harold has the same income after this reform,and that prices do not change.Before declaring which kind of purchaser it will be,∗We refer to all Mungoans bythe gender-neutral pronoun,“it.”Al-though Mungo has two sexes,neither of them is remotelylike either of ours.16BUDGET CONSTRAINT (Ch.2)Harold contemplates the set of commoditybundles that it could afford bymaking one declaration or the other.Let us call a commoditybundle “attainable”if Harold can afford it bydeclaring itself to be a “Blue”and buying the bundle with blue money or if Harold can afford the bundle bydeclaring itself to be a “Red”and buy ing it with red money .On the diagram below,shade in all of the attainable bundles.0510152051015AmbrosiaGum202.13(0)Are Mungoan budgets reallyso fanciful?Can y ou think of sit-uations on earth where people must simultaneouslysatisfymore than onebudget constraint?Is moneythe onlyscarce resource that people use up when consuming?Consumption of manycommoditiestakes time as well as money.People have to simultaneouslysatisfya time budget and a moneybudget.Other examples--people mayhave a calorie budget or a cholesterol budget or an alcohol-intake budget.Chapter 3NAMEPreferencesIntroduction.In the previous section you learned how to use graphs toshow the set of commoditybundles that a consumer can afford.In this section,you learn to put information about the consumer’s preferences on the same kind of graph.Most of the problems ask you to draw indifference curves.Sometimes we give you a formula for the indifference curve.Then all you have to do is graph a known equation.But in some problems,we give you only “qualitative”information about the consumer’s preferences and ask you to sketch indifference curves that are consistent with this information.This requires a little more thought.Don’t be surprised or disappointed if you cannot immediately see the answer when you look at a problem,and don’t expect that you will find the answers hiding somewhere in your textbook.The best way we know to find answers is to “think and doodle.”Draw some axes on scratch paper and label them,then mark a point on your graph and ask yourself,“What other points on the graph would the consumer find indifferent to this point?”If possible,draw a curve connecting such points,making sure that the shape of the line you draw reflects the features required by the problem.This gives you one indifference curve.Now pick another point that is preferred to the first one you drew and draw an indifference curve through it.Example:Jocasta loves to dance and hates housecleaning.She has strictly convex preferences.She prefers dancing to anyother activityand never gets tired of dancing,but the more time she spends cleaning house,the less happyshe is.Let us tryto draw an indifference curve that is consistent with her preferences.There is not enough information here to tell us exactlywhere her indifference curves go,but there is enough information to determine some things about their shape.Take a piece of scratch paper and draw a pair of bel the horizontal axis “Hours per dayof housecleaning.”Label the vertical axis “Hours per dayof dancing.”Mark a point a little ways up the vertical axis and write a 4next to it.At this point,she spends 4hours a daydancing and no time housecleaning.Other points that would be indifferent to this point would have to be points where she did more dancing and more housecleaning.The pain of the extra housekeeping should just compensate for the pleasure of the extra dancing.So an indifference curve for Jocasta must be upward sloping.Because she loves dancing and hates housecleaning,it must be that she prefers all the points above this indifference curve to all of the points on or below it.If Jocasta has strictlyconvex preferences,then it must be that if you draw a line between any two points on the same indifference curve,all the points on the line (except the endpoints)are preferred to the endpoints.For this to be the case,it must be that the indifference curve slopes upward ever more steeplyas y ou move to the right along it.You should convince yourself of this by making some drawings on scratch18PREFERENCES (Ch.3)paper.Draw an upward-sloping curve passing through the point (0,4)and getting steeper as one moves to the right.When you have completed this workout,we hope that you will be able to do the following:•Given the formula for an indifference curve,draw this curve,and find its slope at anypoint on the curve.•Determine whether a consumer prefers one bundle to another or is indifferent between them,given specific indifference curves.•Draw indifference curves for the special cases of perfect substitutes and perfect complements.•Draw indifference curves for someone who dislikes one or both com-modities.•Draw indifference curves for someone who likes goods up to a point but who can get “too much”of one or more goods.•Identifyweaklypreferred sets and determine whether these are con-vex sets and whether preferences are convex.•Know what the marginal rate of substitution is and be able to deter-mine whether an indifference curve exhibits “diminishing marginal rate of substitution.”•Determine whether a preference relation or anyother relation be-tween pairs of things is transitive,whether it is reflexive,and whether it is complete.3.1(0)Charlie likes both apples and bananas.He consumes nothing else.The consumption bundle where Charlie consumes x A bushels of apples per year and x B bushels of bananas per year is written as (x A ,x B ).Last year,Charlie consumed 20bushels of apples and 5bushels of bananas.It happens that the set of consumption bundles (x A ,x B )such that Charlie is indifferent between (x A ,x B )and (20,5)is the set of all bundles such that x B =100/x A .The set of bundles (x A ,x B )such that Charlie is just indifferent between (x A ,x B )and the bundle (10,15)is the set of bundles such that x B =150/x A .(a)On the graph below,plot several points that lie on the indifference curve that passes through the point (20,5),and sketch this curve,using blue ink.Do the same,using red ink,for the indifference curve passing through the point (10,15).(b)Use pencil to shade in the set of commoditybundles that Charlie weaklyprefers to the bundle (10,15).Use blue ink to shade in the set of commoditybundles such that Charlie weaklyprefers (20,5)to these bundles.NAME 19010203040102030ApplesBananas 40For each of the following statements about Charlie’s preferences,write “true”or “false.”(c)(30,5)∼(10,15).True.(d)(10,15) (20,5).True.(e)(20,5) (10,10).True.(f)(24,4) (11,9.1).False.(g)(11,14) (2,49).True.(h)A set is convex if for anytwo points in the set,the line segment between them is also in the set.Is the set of bundles that Charlie weakly prefers to (20,5)a convex set?Yes.(i)Is the set of bundles that Charlie considers inferior to (20,5)a convex set?No.(j)The slope of Charlie’s indifference curve through a point,(x A ,x B ),is known as his marginalrateofsubstitutionat that point.20PREFERENCES (Ch.3)(k)Remember that Charlie’s indifference curve through the point (10,10)has the equation x B =100/x A .Those of you who know calculus will remember that the slope of a curve is just its derivative,which in this case is −100/x 2A .(If you don’t know calculus,you will have to take our word for this.)Find Charlie’s marginal rate of substitution at the point,(10,10).−1.(l)What is his marginal rate of substitution at the point (5,20)?−4.(m)What is his marginal rate of substitution at the point (20,5)?(−.25).(n)Do the indifference curves you have drawn for Charlie exhibit dimin-ishing marginal rate of substitution?Yes.3.2(0)Ambrose consumes onlynuts and berries.Fortunately ,he likes both goods.The consumption bundle where Ambrose consumes x 1units of nuts per week and x 2units of berries per week is written as (x 1,x 2).The set of consumption bundles (x 1,x 2)such that Ambrose is indifferent between (x 1,x 2)and (1,16)is the set of bundles such that x 1≥0,x 2≥0,and x 2=20−4√x 1.The set of bundles (x 1,x 2)such that (x 1,x 2)∼(36,0)is the set of bundles such that x 1≥0,x 2≥0and x 2=24−4√x 1.(a)On the graph below,plot several points that lie on the indifference curve that passes through the point (1,16),and sketch this curve,using blue ink.Do the same,using red ink,for the indifference curve passing through the point (36,0).(b)Use pencil to shade in the set of commoditybundles that Ambrose weaklyprefers to the bundle (1,16).Use red ink to shade in the set of all commoditybundles (x 1,x 2)such that Ambrose weaklyprefers (36,0)to these bundles.Is the set of bundles that Ambrose prefers to (1,16)a convex set?Yes.(c)What is the slope of Ambrose’s indifference curve at the point (9,8)?(Hint Recall from calculus the wayto calculate the slope of a curve.If you don’t know calculus,you will have to draw your diagram carefully and estimate the slope.)−2/3.。

（完整版）范⾥安中级微观经济学中级微观经济学1. 维克⾥拍卖定义：维克⾥拍卖的⽅式类似密封拍卖，但有⼀个重要区别：商品由报价最⾼的竞价⼈获得，但他只需要按第⼆⾼的报价⽀付。

换句话说，报价最⾼的投标⼈得到了拍卖商品，但是他不需要按照他⾃⾝的报价⽀付，⽽是按照报价第⼆⾼的⼈的报价⽀付。

特点：密封报、同时报价、价⾼者得、赢家⽀付次⾼价分析：我们分析⼀个只有两个投标⼈的特殊情形。

这两⼈的对商品的评价分别为 1v 和2v ，他们在纸条上写下的报价分别为1b 和2b 。

投标⼈1的期望收益为：如果21v ＞v ，最⼤化胜出的概率；也就是设置11v b =。

如果21v ＜v ，最⼩化胜出的概率；也就是设置11v b =。

任意情况，Telling the truth is best 。

2. 帕累托有效率如果可以找到⼀种配置，在其他⼈的境况没有变坏的情况下，的确能使⼀些⼈的境况变得更好⼀些，那么，这就叫做帕累托改进；如果⼀种配置⽅法存在帕累托改进，他就称为帕累托低效率；如果⼀种配置⽅法不存在任何的帕累托改进，他就称为帕累托有效率的。

3. 价格歧视，第⼀、⼆、三级价格歧视1.价格歧视：按不同价格销售不同单位产品的做法称为价格歧视 2.⼀、⼆、三级价格歧视：第⼀级价格歧视：是指垄断企业按不同价格出售不同产量，⽽且这些价格可能因⼈⽽异。

这种价格歧视有时⼜称为完全价格歧视。

第⼆级价格歧视：是指，垄断企业按不同价格出售不同产量，但是购买相同数量的每个⼈⽀付价格是相同的。

因此，价格按购买数量制定，⽽不是因⼈⽽异。

最常见的情形是⼤宗购买时可以享受折扣。

第三级价格歧视：是指垄断企业的销售价格因⼈⽽异，但对于同⼀个⼈来说，每单位产品的售价是相同的。

这种价格歧视最常见。

例如:对⽼年⼈打折，对学⽣打折等。

4. 消费者剩余消费者剩余：是指购买者的⽀付意愿减去购买者的实际⽀付量。

消费者剩余衡量了购买者⾃⼰感觉到所获得的额外收益。

5. 显⽰偏好原理1.显⽰偏好：假定：（1）所有消费者的偏好都是严格凸性的，因此对于⼀个预算线来说都有且只有⼀个最优消费束。

第5章 选 择1．假定两种商品是完全替代品，商品2的需求函数是什么？答：假设完全替代的效用函数是：u （x 1，x 2）＝x 1＋x 2，（为了简化计算，这里只考虑替代比例为1:1的情况）在预算约束下，消费者选择效用最大化，即：12120,0max x x x x ≥≥+1122..s t p x p x m +=由约束条件，解得x 1＝（m －p 2x 2）/p 1，同时由于x 1≥0，则（m －p 2x 2）/p 1≥0，即：x 2≤m/p 2。

将x 1的表达式以及约束条件x 2≤m/p 2代入效用函数后，得到：22222220111max 1x m p m p x p m x x p p p ≤≤⎛⎫-+=+- ⎪⎝⎭ 从而解得： 12212212212 0 (,,)0/ / p p x p p m m p p p m p p p <⎧⎪==⎨⎪>⎩到间的任何值 如图5-1所示。

图5-1 完全替代商品的需求曲线2．假设无差异曲线是一条斜率为－b的直线，并且给定任意的价格p1、p2和收入m，那么，消费者的最优选择是什么？答：如图5-2所示，比较预算线与无差异曲线的斜率可知，当p1/p2＞b时，消费者的最优选择为只购买商品2；当p1/p2＜b时，消费者的最优选择为只购买商品1；当p1/p2＝b时，预算线上的任意消费组合都是消费者的最优选择。

图5-2 完全替代偏好的最优选择3．假定一个消费者在每一杯咖啡里总是加2汤匙糖。

如果每汤匙糖的价格为p1，每杯咖啡的价格为p2，消费者花费在咖啡和糖上的总额为m美元，那么，他或她将打算购买多少咖啡和糖？答：设x1表示糖，x2表示咖啡，消费者的效用函数为：u（x1，x2）＝min{x1，2x2}，那么消费者的最优选择总是满足：2x2＝x1，将这一条件代入预算线方程p1x1＋p2x2＝m中，可以得到x1＝2m/（2p1＋p2）、x2＝m/（2p1＋p2）。

第一部分 消费者选择理论1.有两种商品，x1和x2，价格分别为p1和p2，收入为m 。

当11x x ≥时，政府加数量税t,画出预算集并写出预算线2. 消费者消费两种商品（x1，x2），如果花同样多的钱可以买（4，6）或（12，2），写出预算线的表达式。

3．重新描述中国粮价改革（1）假设没有任何市场干预，中国的粮价为每斤0。

4元，每人收入为100元。

把粮食消费量计为x ，在其它商品上的开支为y ，写出预算线，并画图。

（2）假设每人得到30斤粮票，可以凭票以0。

2元的价格买粮食，再写预算约束，画图。

（3）假设取消粮票，补贴每人6元钱，写预算约束并画图。

4． 证两条无差异曲线不能相交5． 一元纸币（x1）和五元纸币（x2）的边际替代率是多少？6． 若商品1为中性商品，则它对商品2的边际替代率？7. 写出下列情形的效用函数，画出无差异曲线，并在给定价格（p 1，p 2）和收入（m ）的情形下求最优解。

（1）x 1=一元纸币，x 2=五元纸币。

（2）x 1=一杯咖啡，x 2=一勺糖, 消费者喜欢在每杯咖啡加两勺糖。

8. 解最优选择（1） 21212(,)u x x x x =⋅（2）2u x =+9. 对下列效用函数推导对商品1的需求函数，反需求函数，恩格尔曲线；在图上大致画出价格提供曲线，收入提供曲线；说明商品一是否正常品、劣质品、一般商品、吉芬商品，商品二与商品一是替代还是互补关系。

（1）212x x u +=（2）()212,m in x x u =（3）b a x x u 21⋅=（4） 12ln u x x =+,10. 当偏好为完全替代时，计算当价格变化时的收入效用和替代效用（注意分情况讨论）。

11. 给定效用函数 (,)x y xy =，p x =3，p y =4，m=60，求当p y 降为3时价格变化引起的替代效应和收入效应。

12. 用显示偏好的弱公理说明为什么Slutsky 替代效应为负。

范里安中级微观经济学习题集答案在范里安中级微观经济学习题集中，以下是答案解析：1. 供给和需求对于供给和需求的理解，我们可以从市场上某个商品的定价和交易量来进行分析。

供给表示某个商品或服务在一定时间内，卖方愿意以不同价格提供的数量。

需求表示某个商品或服务在一定时间内，买方愿意以不同价格购买的数量。

供给和需求的交互作用决定了市场上商品的价格和交易量。

在供需关系中，如果供给增加，需求不变，价格会下降，交易量会增加。

相反，如果供给减少，需求不变，价格会上升，交易量会减少。

如果需求增加，供给不变，价格会上升，交易量会增加。

相反，如果需求减少，供给不变，价格会下降，交易量会减少。

2. 市场均衡市场均衡是指在供求关系下，商品的价格和交易量达到一种稳定状态的情况。

当供给和需求达到均衡时，市场上的商品价格不再发生明显的变化。

市场均衡是通过供给曲线和需求曲线的相交来确定的。

在市场均衡的状态下，供给量等于需求量，市场价格也就是均衡价格。

这个均衡价格和交易量反映了供需双方的心理预期。

3. 稀缺性和选择稀缺性是指人们的需求超过可用资源的总量。

由于资源是有限的，人们不得不做出选择。

选择性是指在有限的资源下，人们必须做出取舍来满足自己的需求。

例如，一个人在有限的时间内可以选择看电视、读书还是锻炼身体。

人们在做出选择时，会比较不同选择之间的成本和收益，并选择能够最大化收益的选项。

4. 机会成本机会成本是指在做出某种选择时，放弃的最好的替代选择所产生的成本。

换句话说，机会成本是指因选择某种行动而放弃的下一最有价值的选择。

例如，一个人在选择上班的同时，放弃了进行休闲娱乐的时间。

这段放弃休闲娱乐的时间的价值就是他的机会成本。

5. 弹性在微观经济学中，弹性是指需求或供给对价格或收入变化的敏感程度。

需求弹性分为价格弹性和收入弹性。

价格弹性衡量了需求对价格变化的敏感程度，收入弹性衡量了需求对收入变化的敏感程度。

供给弹性衡量了供给对价格变化的敏感程度。

目　录第1章　市　场第2章　预算约束第3章　偏　好第4章　效　用第5章　选　择第6章　需　求第7章　显示偏好第8章　斯勒茨基方程第9章　购买和销售第10章　跨时期选择第11章　资产市场第12章　不确定性第13章　风险资产第14章　消费者剩余第15章　市场需求第16章　均　衡第17章　拍　卖第18章　技　术第19章　利润最大化第20章　成本最小化第21章　成本曲线第22章　厂商供给第23章　行业供给第24章　垄　断第25章　垄断行为第26章　要素市场第27章　寡头垄断第28章　博弈论第29章　博弈论的应用第30章　行为经济学第31章　交　换第32章　生　产第33章　福　利第34章　外部效应第35章　信息技术第36章　公共物品第37章　不对称信息第1章　市　场1假设在房屋租赁市场上，前25个消费者租用商品房的保留价格为500美元，第26个消费者租用商品房的保留价格为200美元，需求曲线呈什么形状？答：此时需求曲线呈阶梯状。

具体的讲，当价格高于500美元时，需求为0，价格介于200美元到500美元之间时，需求为25套，当价格小于等于200美元时，需求为26套。

相应的数学表达式为：相应的需求曲线如图1-1所示。

图1-1　租赁房屋的需求曲线2在第1题中，假如只有24套住房可以出租，均衡价格是多少？如果有26套住房可出租，均衡价格又是多少？如果有25套住房可出租，均衡价格是多少？答：（1）假如只有24套住房可以出租，那么均衡价格为500美元。

这是因为：均衡时，供给曲线和需求曲线相交，交点的纵坐标对应的就是均衡价格，如图1-2的点所示。

特别的，图1-2中的需求曲线和图1-1相同。

（2）如果市场上有26套住房出租，均衡价格为0美元（含）到200美元（含）之间的任意数值。

理由同（1），如图1-2的点所示。

（3）如果只有25套住房可以出租，均衡价格为200美元（含）到500美元（含）之间的任意数值。

理由同（1），如图1-2的点所示。

第2章预算约束1.消费者的最初预算线是p1x1+p2x2=m。

接着，商品1的价格提高了1倍，商品2的价格提高了7倍，收入增加了3倍。

根据原先的价格和收入写出新的预算线的方程。

2.如果商品2的价格上涨了，而商品1的价格和收入保持不变，预算线会有什么变化？3.如果商品1的价格上涨了1倍，商品2的价格上涨了2倍，预算线是变得平缓了还是变得陡峭了？4.计价物的定义是什么?5.假设政府起初对每加仑汽油征税15美分，后来，又决定对每加仑汽油补贴7美分。

这两种方法混合运用后的税收是多少？6.假设预算方程是p1x1+p2x2=m。

如果政府决定征收u单位的总额税、对商品1征收t单位的从量税，以及对商品2进行从量补贴s，新预算线的公式是什么？7.如果消费者的收入增加了，同时有一种商品的价格下降了，那么消费者的境况会与原来一样好吗？1.如果我们有一次看到，某消费者在（y1,y2）可以同时得到的情况下选择了（x1,x2）,那么，（x1,x2）>（y1,y2）的结论正确吗？2.假设有三个人A,B和C，身高关系为“至少和…一样高”，比如“A至少和B一样高”。

这样的关系是传递的吗？是完备的吗？3.假设有三个人A,B和C，身高关系为“严格高于”。

这样的关系是传递的吗？是反身的吗？是完备的吗？4.某大学橄榄球教练说，任意给定两个前锋比如 A和B，他永远偏好身材更高大和速度更快的那个。

他的这种偏好关系是传递的吗？是完备的吗？5.某条无差异曲线能否与自身相交？例如，图3.2能否是一条无差异曲线而不是两条？6.如果偏好是单调的，能否把图3.2看成一条无差异曲线而不是两条？7.如果辣香肠和凤尾鱼都是厌恶品，那么无差异曲线的斜率为正还是负？8.解释为什么凸偏好意味着“平均束好于端点束”。

11.举例说明你的偏好在什么样的情形下为凹的。

1.课文中说，将某数字变为它的奇次幂是一种单调变换。

那么，将其变为它的偶次幂是单调变换吗？（提示：要考虑类似f(u)=u2的情形。

《中级微观经济学》第一、二章作业《中级微观经济学》1第一、二章作业1.1.假设25 个人的保留价格为500美元，第26个人持有的保留价格为200美元，需求曲线呈什么形状？1.2.在上述例子中，假如只有24 套房可以出租，均衡价格是多少？如果有26 套房可出租，均衡价格又是多少？如果有25 套房可以出租，均衡价格是多少？1.3.假定持有不同的保留价格，为什么市场需求曲线向下倾斜？1教材为范里安《微观经济学：现代观点》第九版，习题可能与第八版略有不同1.4.在本书中，我们假设公寓购买者都者来自内城区的人。

如果公寓购买者都来自于外城区的人，内城区住房的价格会发生怎么样的变化？.1.5.假设现在公寓的购买者都是内城区的人，但是每一公寓由两套住房构成，住房的价格会发生什么样的变化。

1.6.设想一下，征税会对长期内的建房数量产生什么影响。

1.7.假设需求曲线为D( p) =100-2 p .如果垄断者有60 个公寓，他将如何定价？他将租出多少公寓？如果他有40 个公寓，他将如何定价？他将租出多少公寓？1.8.如果我们的租金管制模型允许不受限制地转租，谁最终获得内环的公寓？这个结果是帕累托有效率的吗？2.1.消费者的初始预算线为p1x1+p2x2-m。

现在商品1 的价格提高了1倍，商品2的价格提升了7倍，收入提升了3倍。

根据原先的价格和收入写出新的预算线方程。

2.2.如果商品2 的价格上升，但商品1 的价格和收入保持不变，那么预算线如何变动？2.3.如果商品1 的价格上涨了1倍，商品2 的价格上涨了2倍，预算线变得更平坦还是更陡峭？2.4.计价物的定义是什么？2.5.假设政府最初对每加仑汽油征税15 分钱，后来又决定对每加仑汽油给与7分钱的补贴。

这种税收和补贴联合使用的方式等价于对每加仑汽油征多少税？2.6.假设预算线方程为p1x1+p2x2=m 。

现在政府决定：对消费者征收定额税，税额为u ；对每单位商品1 征收t 元从量税；对每单位商品2 给与s 元补贴。

可编辑修改精选全文完整版2、假设某消费者的效用函数为U XY =，X 和Y 表示两种商品，当效用为20单位、X 商品的消费量为5时，Y 商品的消费量是多少？这一商品消费组合对应的边际替代率是多少？如果这时的组合是达到消费者均衡的组合，那么X 和Y 两种商品的价格之比应为多少？① ∵U XY =当错误!未找到引用源。

=20时，由X=5得：错误!未找到引用源。

=80。

② 边际替代率Y X MU MU错误!未找到引用源。

11221=2X MU X Y -③ 达到均衡时，故：错误!未找到引用源。

. 3、已知效用函数为1U X Y αα-=，求商品的边际替代率MRS XY 和MRS YX ，并求当X 和Y 的数量分别为4和12时的边际替代率。

解：11113(1)(1)(1)(1)(1)(1)3X XY Y Y YX X MU X Y Y MRS MU X Y X MU X Y X MRS MU X Y Y αααααααααααααααααααα------====------====4、假设某消费者的效用函数为22(,)U U X Y X Y ==，消费者的预算线是X Y I P X P Y =+，试求该约束条件下的最优化问题，并推导出消费者均衡的一阶条件，再推导出用参数表示的X 和Y 的需求函数。

解：22max ..X YU X Y s t I P X P Y ⎧=⎨=+⎩ 22()X Y L X Y I P X P Y λ=+--220X L XY P Xλ∂=-=∂……（1） 220Y L X Y P Yλ∂=-=∂……（2） 0X Y L I P X P Y λ∂=--=∂……（3） （1）除于（2）可得：X YP Y X P =……（4） 由（4）得：X YP Y X P =……（5） 将（5）代入（3）得：2XI X P =……（6） 将（6）代入（5）得： 2Y I Y P =……（7） 答：（4）式为一阶条件，（6）、（7）式为需求函数。