微观14

经济学原理（微观经济学分册）考研真题精选14(总分：100.00，做题时间：60分钟)一、论述题(总题数：6，分数：100.00)1.试论述完全竞争厂商的短期均衡理论。

（分数：10.00）__________________________________________________________________________________________正确答案：(在完全竞争厂商的短期生产中，市场的价格是给定的，而且，生产中的不变要素投人量是无法变动的，即生产规模是给定的。

因此，在短期，厂商是在给定的生产规模下，通过对产量的调整来实现MR=S 胁：的利润最大化的均衡条件。

当厂商实现MR=SMC时，有可能获得利润，也可能亏损。

完全竞争厂商短期均衡的不同情况如图14—11所示。

(1)经济利润大于零的短期均衡当市场价格为P1，时，MR与MC相交于A点(P1=MR)。

这时P1>AC，厂商可获得超额利润。

π=Q1x(P-AC)=Q1xAB，即矩形ABGP1的面积。

所以厂商将按MR=MC所确定的产量点Q1。

进行生产．以获得最大利润。

(2)经济利润等于零(即仅获得正常利润)的短期均衡当市场价格为P2时，MR与MC相交于AC的最低点C。

在C点，P2=AC，π=0．厂商收支相抵，既无盈余也无亏损。

AC的最低点C称为利润零点或短期收支相抵点．或扯平点。

此时。

厂商按MR=MC所确定的产量Q2进行生产．在其他产量点上，厂商都将出现亏损。

(3)亏损但继续生产经营的短期均衡当市场价格为P3时，MR与MC相交于D点，这时AC>P3>AVC，厂商亏损，但厂商仍可生产。

因为价格大于平均可变成本，说明厂商在补偿全部的可变成本外，尚可收回部分固定成本，使亏损总额减少一些。

因此，厂商按MR=MC的原则，决定产量Q3，其亏损最小。

(4)亏损并停止生产经营的短期均衡(停止营业点)当市场价格为P4时，MR与MC相交于AVC的最低点E，这时AC>P4=AVC，此时，厂商的平均收益AR等于平均可变成本AVC，厂商可以继续生产，也可以不生产，也就是说，厂商生产或不生产的结果都是一样的，厂商亏损全部固定成本。

Session 4　经济学：微观分析LOS 14　需求和供给分析：消费者需求考试重点在本章节，将介绍效用理论，即模型化了的消费者选择。

比较重要的是消费者的偏好曲线，即一条代表消费者对各种可供选择的商品组合的偏好曲线。

在资产组合管理中也会见到类似的分析方法。

关于劣质品的概念是非常有用的，特别是在考虑经济衰退，人们的平均收入都下降时，消费者如何选择商品和行业来增加收入的决策。

另一方面，考察由于价格变动带来的收入替代效应，吉芬品和凡勃伦商品是非常好的例子LOS 14．a：描述消费者选择理论和效用理论。

效用理论即消费者行为理论，是消费者根据对各种商品组合偏好分配他们的收入已达到相对满足程度的最大化。

效用用来衡量消费者从消费某一种特定商品组合中获取的满足感。

效用理论是消费者选择理论中的重要部分，即将消费者的意愿和偏好与他们真实能够购买得到的商品和服务联系在一起。

效用函数的表示形式为效用=U（Q A，Q B，……，Q N），变量是商品A到N的消费数量。

假设消费量没有负数（但可能有一些为0），在其他变量保持不变时，一个变量增加将会导致效用增加。

这被称之为不满足状态，这种状态可以简单地被描述为当其他事物相同时，多总比少好。

如果人们偏好少比多好，则意味着没有拥有一个有价值的事物，而是拥有一个没有用的事物，如垃圾，这时我们甚至愿意花钱处理它（减少它的数量）。

效用是用序数来表示的，而不是用基数来表示。

假设有两种商品组合，组合1有2个披萨和20瓶啤酒，组合2有3个披萨和15瓶啤酒。

如果组合1的效用是100，组合2的效用是200，我们可以说组合2比组合1更受欢迎，因为200大于l00。

但是我们不能推断组合2给人们带来的满足感是组合1的2倍，也不能说组合2的效用等于两个组合1的效用。

如果组合1的效用是4001，组合2的效用是4001，我们可以准确的得到同样的结果，简单来讲即组合2比组合1更受人们喜爱。

LOS 14．b：描述在决策制定中无差异曲线、机会组合和预算约束的用途。

回归模型回归分析是研究一个变量（被解释变量）关于另一个（些）变量（解释变量）的具体依赖关系的计算方法和理论。

从一组样本数据出发，确定变量之间的数学关系式对这些关系式的可信程度进行各种统计检验，并从影响某一特定变量的诸多变量中找出哪些变量的影响显著，哪些不显著。

利用所求的关系式，根据一个或几个变量的取值来预测或控制另一个特定变量的取值，并给出这种预测或控制的精确程度。

其用意：在于通过后者的已知或设定值，去估计和（或）预测前者的（总体）均值。

时间序列模型对某一个或一组变量x(t)进行观察测量，将在一系列时刻t1, t2, …, tn (t为自变量）按照时间次序排列，并用于解释变量和相互关系的数学表达式。

<t2<…< tn="" )="" 所得到的离散数字组成序列集合x(t1),="" x(t2),="" …,="" x(tn)，我们称之为时间序列，这种有时间意义的序列也称为动态数据。

时间序列分析是根据系统观测得到的时间序列数据，通过曲线拟合和参数估计来建立数学模型，从而对客观事实进行描述、分析、预测以及作出决策。

神经网络模型神经网络模型是以神经元的数学模型为基础来描述的。

神经网络模型由网络拓扑、节点特点和学习规则来表示。

在经济应用中，能对商品价格、股票价格和企业的可信度等进行短期预测。

投入产出模型投入产出数学模型是通过编制投入产出表，运用线性代数工具建立数学模型，从而揭示国民经济各部门、再生产各环节之间的内在联系，并据此进行经济分析、预测和安排预算计划。

按计量单位不同，该模型可分为价值型和实物型。

灰色模型灰色模型（grey models）就是通过少量的、不完全的信息，建立灰色微分预测模型，对事物发展规律作出模糊性的长期描述（模糊预测领域中理论、方法较为完善的预测学分支）。

如果一个系统具有层次、结构关系的模糊性，动态变化的随机性，指标数据的不完备或不确定性，则称这些特性为灰色性。

曼昆《经济学原理》（微观）第五版测试题库（14）（1）Chapter 14Firms in Competitive MarketsTRUE/FALSE1. For a firm operating in a perfectly competitive industry, total revenue, marginal revenue, and average revenue are all equal.ANS: F DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Average revenue | Marginal rev-enueMSC: Interpretive2. For a firm operating in a perfectly competitive industry, marginal reve-nue and average revenue are equal.ANS: T DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Average revenue | Marginal rev-enueMSC: Interpretive3. If a firm notices that its average revenue equals the current market price, that firm must be participating in a competitive market.ANS: F DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Average revenueMSC: Interpretive4. A profit-maximizing firm in a competitive market will increase produc-tion when average revenue exceeds marginal cost. ANS: T DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Average revenueMSC: Interpretive5. Because there are many buyers and sellers in a perfectly competitive market, no one seller can influence the market price. ANS: T DIF: 1 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Definitional6. Firms operating in perfectly competitive markets try to maximize prof-its.ANS: T DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Profit maximization929MSC: Applicative7. In competitive markets, firms that raise their prices are typically re-warded with larger profits.ANS: F DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive8. When an individual firm in a competitive market increases its produc-tion, it is likely that the market price will fall. ANS: F DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive9. In a competitive market, firms are unable to differentiate their product from that of other producers.ANS: T DIF: 1 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive10. Firms in a competitive market are said to be price takers because there are many sellers in the market and the goods offered by the firms are very similar if not identical.ANS: T DIF: 2 REF: 14-1 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive11. A firm's incentive to compare marginal revenue and marginal cost is an application of the principle that rational people think at the margin. ANS: T DIF: 1 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive12. By comparing the marginal revenue and marginal cost from each unit produced, a firm in a competitive market can determine the profit-maximizing level of production.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretiveword⽂档可⾃由复制编辑Chapter 14/Firms in Competitive Markets 931 13. Firms operating in perfectly competitive markets produce an output level where marginal revenue equals marginal cost.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Marginal revenueMSC: Applicative14. A firm is currently producing 100 units of output per day. The man-ager reports to the owner that producing the 100th unit costs the firm $5. The firm can sell the 100th unit for $4.75. The firm should continue to pro-duce 100 units in order to maximize its profits (or minimize its losses). ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Analytical15. A firm is currently producing 100 units of output per day. The man-ager reports to the owner that producing the 100th unit costs the firm $5. The firm can sell the 100th unit for $5. The firm should continue to produce 100 units in order to maximize its profits (or minimize its losses).ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Analytical16. A firm is currently producing 100 units of output per day. The man-ager reports to the owner that producing the 100th unit costs the firm $5. The firm can sell the unit for $6. The firm should produce more than 100 units in order to maximize its profits (or minimize its losses).ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Analytical17. A dairy farmer must be able to calculate sunk costs in order to deter-mine how much revenue the farm receives for the typical gallon of milk. ANS: F DIF: 1 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Sunk costs MSC: I nterpretive18. Because nothing can be done about sunk costs, they are irrelevant to decisions about business strategy.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Sunk costs MSC: I nterpretive19. A miniature golf course is a good example of where fixed costs be-come relevant to the decision of when to open and when to close for the season.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Sunk costs MSC: I nterpretive20. A popular resort restaurant will maximize profits if it chooses to stay open during the less-crowded “off season” when its total revenues exceed its variable costs.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Sunk costs MSC: I nterpretive21. All firms maximize profits by producing an output level where marginal revenue equals marginal cost; for firms operating in perfectly competitive in-dustries, maximizing profits also means producing an output level where price equals marginal cost.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive22. A firm operating in a perfectly competitive industry will continue to op-erate in the short run but earn losses if the market price is less than that firm’s average total cost but greater than the firm’s average variable cost. ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretive23. A firm operating in a perfectly competitive industry will continue to op-erate in the short run but earn losses if the market price is less than that firm’s average variable co st.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretive24. A firm operating in a perfectly competitive industry will shut down in the short run but earn losses if the market price is less than that firm’s aver-age variable cost.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretiveword⽂档可⾃由复制编辑Chapter 14/Firms in Competitive Markets 933 25. In the short run, a firm should exit the industry if its marginal cost ex-ceeds its marginal revenue.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretive26. In making a short-run profit-maximizing production decision, the firm must consider both fixed and variable cost. ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive27. A firm will shut down in the short run if revenue is not sufficient to cov-er its variable costs of production.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Shut down MSC: I nterpretive28. Suppose a firm is considering producing zero units of output. We call this shutting down in the short run and exiting an industry in the long run. ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Shut down MSC: I nterpretive29. Suppose a firm is considering producing zero units of output. We call this exiting an industry in the short run and shutting down in the long run. ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Shut down MSC: I nterpretive30. A firm will shut down in the short run if revenue is not sufficient to cov-er all of its fixed costs of production.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Shut down MSC: I nterpretive31. The supply curve of a firm in a competitive market is the average va-riable cost curve above the minimum of marginal cost.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretive32. When a profit-maximizing firm in a competitive market experiences rising prices, it will respond with an increase in production.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive33. The marginal firm in a competitive market will earn zero economic profit in the long run.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Economic profitMSC: Interpretive34. A profit-maximizing firm in a competitive market will earn zero ac-counting profits in the long run.ANS: F DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Accounting profitMSC: Interpretive35. In the long run, when price is less than average total cost for all possi-ble levels of production, a firm in a competitive market will choose to exit (or not enter) the market.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive36. In the long run, when price is greater than average total cost, some firms in a competitive market will choose to enter the market.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive37. In the long run, a firm should exit the industry if its total costs exceed its total revenues.ANS: T DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximizationMSC: Interpretive38. When a resource used in the production of a good sold in a competi-tive market is available in only limited quantities, the long-run supply curve is likely to be upward sloping.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretiveword⽂档可⾃由复制编辑Chapter 14/Firms in Competitive Markets 935 39. A firm operating in a perfectly competitive industry will continue to op-erate if it earns zero economic profits because it is likely to be earning posi-tive accounting profits.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive40. A firm operating in a perfectly competitive industry will shut down in the short run if its economic profits fall to zero because it is likely to be earn-ing negative accounting profits.ANS: F DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Competitive marketsMSC: Interpretive41. A firm operating in a perfectly competitive market may earn positive, negative, or zero economic profit in the long run. ANS: F DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Long-run supply curveMSC: Interpretive42. A firm operating in a perfectly competitive market may earn positive, negative, or zero economic profit in the short run. ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Long-run supply curveMSC: Interpretive43. A firm operating in a perfectly competitive market earns zero economic profit in the long run but remains in business because the firm’s revenues cover the business owners’ opportunity costs.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive44. A competitive market will typically experience entry and exit until ac-counting profits are zero.ANS: F DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive45. The long-run equilibrium in a competitive market characterized by firms with identical costs is generally characterized by firms operating at effi-cient scale.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive46. In the long run, a competitive market with 1,000 identical firms will ex-perience an equilibrium price equal to the minimum of each firm's average total cost.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive47. In a long-run equilibrium where firms have identical costs, it is possible that some firms in a competitive market are making a positive economic prof-it.ANS: F DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive48. When economic profits are zero in equilibrium, the firm's revenue must be sufficient to cover all opportunity costs. ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Zero-profit conditionMSC: Interpretive49. The short-run supply curve in a competitive market must be more elastic than the long-run supply curve.ANS: F DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: Interpretive50. The long-run supply curve in a competitive market is more elastic than the short-run supply curve.ANS: T DIF: 2 REF: 14-3 NAT: AnalyticLOC: Perfect competition TOP: Supply curveMSC: InterpretiveSHORT ANSWERword⽂档可⾃由复制编辑Chapter 14/Firms in Competitive Markets 937 1. Describe the difference between average revenue and marginal reve-nue. Why are both of these revenue measures important to a prof-it-maximizing firm?ANS:Average revenue is total revenue divided by the quantity of output. Marginal revenue is the change in total revenue from the sale of each additional unit of output. Marginal revenue is used to determine the profit-maximizing level of production, and average revenue is used to help determine the level of profits. Note that for all firms, price equals average revenue because AR=(PxQ)/Q=P. But only for a firm operating in a perfectly competitive industry does price al-so equal marginal revenue.DIF: 2 REF: 14-1 NAT: Analytic LOC: Perfect competitionTOP: Price MSC: D efinitional2. List and describe the characteristics of a perfectly competitive market. ANS:There are many buyers and sellers in the market. The goods offered by the various sellers are largely the same. Firms can freely enter or exit the market. DIF: 2 REF: 14-1 NAT: Analytic LOC: Perfect competitionTOP: Competitive markets MSC: D efinitional3. Why would a firm in a perfectly competitive market always choose to set its price equal to the current market price? If a firm set its price below the current market price, what effect would this have on the market?ANS:The firm could not sell any more of its product at a lower price than it could sell at the market price. As a result, it would needlessly forgo revenue if it set a price below the market price. If the firm set a higher price, it would not sell anything at all because a competitive market has many sellers who would supply the product at the market price.DIF: 2 REF: 14-1 NAT: Analytic LOC: Perfect competitionTOP: Profit maximization MSC: A nalytical4. Use a graph to demonstrate the circumstances that would prevail in a competitive market where firms are earning economic profits. Can this sce-nario be maintained in the long run? Explain your answer.ANS:In a competitive market where firms are earning economic profits, new firms will have an incentive to enter the market. This entry will expand the number of firms, increase the quantity of the good supplied, and drive down pricesword ⽂档可⾃由复制编辑 and profits. Entry will cease once firms are producing the output level where price equals the minimum of the average total cost curve, meaning that eachfirm earns zero economic profits in the long run.DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximization MSC: A nalytical5. Explain how a firm in a competitive market identifies the prof-it-maximizing level of production. When should the firm raise production, and when should the firm lower production? ANS:The firm selects the level of output at which marginal revenue is equal tomarginal cost. If MR > MC, profit will increase if the firm increases Q. If MR < MC, profit will increase if the firm decreases Q. DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximization MSC: A nalytical6. News reports from the western United States occasionally report inci-dents of cattle ranchers slaughtering a large number of newborn calves and burying them in mass graves rather than transporting them to markets. As-suming that this is rational behavior by profit-maximizing "firms," explain what economic factors may influence such behavior.ANS:If the selling price is not sufficient to cover the variable cost of sending the calves to market, this (potentially emotionally upsetting) behavior makes economic sense.DIF: 2 REF: 14-2 NAT: AnalyticLOC: Perfect competition TOP: Profit maximization MSC: A nalytical。

Chapter 14: Consumer’s SurplusIntermediate Microeconomics:A Modern Approach (7th Edition)Hal R. Varian(University of California at Berkeley)第14章:消费者消费者剩余剩余(含习题含习题详细详细详细解答解答)中级微观经济学:现代方法（第7版）范里安 著（加州大学伯克利）曹乾 译（东南大学 caoqianseu@ ）简短说明：翻译此书的原因是教学的需要，当然也因为对现行中文翻译版教材的不满，范里安的书是一碗香喷喷的米饭，但市场流行的翻译版却充满了沙子（翻译生硬而且错误颇多）。

我在美国流浪期间翻译了此书的大部分。

仅供教学和学习参考。

14消费者剩余在前面几章，我们已经知道如何从消费者不可观测的偏好或效用函数，推导出他的需求函数。

但在实践中，我们通常关心相反的问题——如何从观察到的消费者的需求行为估测他的偏好或效用。

事实上，我们在第5章和第7章已分析了这样的问题。

在第5章，我们学习了如何从消费者需求的观测数据估计效用函数的参数。

比如，在柯布-道格拉斯类型的偏好中，我们可以估计出描述消费者选择行为的效用函数。

我们是如何做到这一点的？只要计算每种商品的支出占消费者收入的比例即可。

根据推导出的效用函数，我们可以估计消费的变动。

在第7章，我们从消费者可观测到的选择行为入手，阐述了如何使用显示偏好这个工具还原消费者产生上述行为的潜在偏好。

还原出的无差异曲线可用来估测消费变动。

在本章我们介绍从可观测的需求行为推知消费者的效用的其他一些方法。

尽管有些方法不象第5章和第7章的方法那样具有一般性，但以后你就会知道在本书后面的内容中，本章介绍的方法比较有用。

我们从一种特殊的需求行为入手分析，这种需求行为可以让我们比较容易地还原效用。

然后，我们再分析偏好和需求行为更一般的情形。

14.1离散商品的需求第6章我们介绍过拟线性效用情形下的离散商品的需求问题，我们就从这个问题开始分析。

蔡继明《微观经济学（第2版）第14章公共选择跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

1．解释下列基本概念：私人选择、公共选择、投票交易、寻租。

答：略。

2．说明阿罗定理及其含义。

答：阿罗的不可能性定理是指试图找出一套规则（或程序），以从一定的社会状况下的个人选择顺序中推导出符合某种理性条件的社会选择顺序，一般是办不到的。

阿罗不可能定理包含两项重要假设：每个人的偏好是可以排序的；每个人的偏好次序是传递的。

阿罗首先定义了阿罗首先假定了从表面上看社会偏好应该服从的六个无可非议的公理：①所有的社会状态一定可以排序；②社会排序一定是可传递的；③排序与个人偏好正相关；④如果出现新的可行社会状态，不应该影响起初的社会状态排序；⑤不存在独裁，或者说个人不能把自己的偏好强加于社会；⑥没有与个人偏好无关的排序。

阿罗证明，尽管上述6公理从表面上看都是合理的，但并不存在同时服从上述6个条件的一般社会关系，即：社会偏好并不总是同时满足上述6公理。

此即阿罗定理。

阿罗证明了不存在一个选择规则或选择程序能够同时满足上面六个条件，这表明由个人选择合乎逻辑地转化为社会选择的过程包含巨大的困难。

根据阿罗不可能性定理，在非独裁的情况下，不可能存在有适用于所有偏好类型的社会福利函数。

同时，它还意味着不能从不同个人的偏好中合理地形成社会偏好。

换句话说，一般意义上的社会福利函数并不存在，这表明，西方经济学没有能彻底的解决资源配置问题。

3．说明中间投票人定理及其带来的问题。

答：中间投票人定理是指如果在一个多数决策的模型中，个人偏好都是单峰的，则反映中间投票人意愿的那种政策会最终获胜，因为选择该政策会使一个团体的福利损失最小。

尼科尔森《微观经济理论-基本原理与扩展》（第9版）第14章 不完全竞争市场的传统模型课后习题详解跨考网独家整理最全经济学考研真题，经济学考研课后习题解析资料库，您可以在这里查阅历年经济学考研真题，经济学考研课后习题，经济学考研参考书等内容，更有跨考考研历年辅导的经济学学哥学姐的经济学考研经验，从前辈中获得的经验对初学者来说是宝贵的财富，这或许能帮你少走弯路，躲开一些陷阱。

以下内容为跨考网独家整理，如您还需更多考研资料，可选择经济学一对一在线咨询进行咨询。

1．为了简单起见，假设垄断者没有生产成本且它所面临的需求曲线由下式给定：150Q P =- （1）计算这一垄断者利润最大化时的价格—产量组合，并计算该厂商的垄断利润。

（2）假设第二个厂商进入了市场。

令1q 为第一个厂商的产出，2q 为第二个厂商的产出。

市场需求由下式给出12150q q P +=-假设第二个厂商也没有生产成本，运用双头垄断的古诺模型，确定一下利润最大化时每个厂商的产出水平及市场价格，并且计算每个厂商的利润。

（3）怎样把（1）与（2）中结果与完全竞争市场中的价格—产量组合相比较？画出需求曲线与边际收益曲线图形，并且指明需求曲线上的三个不同的价格—产量组合。

解：（1）因为150Q P =-，所以反需求曲线为150P Q =-，则该垄断者的利润函数为：()2150150PQ C Q Q Q Q π=-=-=-+利润最大化的一阶条件为：d 21500d Q Qπ=-+=，解得75Q =。

此时利润最大化时的价格为15075P Q =-=； 该厂商的垄断利润为21505625Q Q π=-+=。

（2）对于厂商1而言，其利润函数为：()11121150Pq C q q q π=-=--利润最大化的一阶条件为：112115020q q q π∂=--=∂，因而厂商1的反应函数为： 12750.5q q =- ①同理可得厂商2的反应函数为：21750.5q q =- ② 在古诺竞争均衡时，有①、②两式同时成立，因而可以解得古诺竞争均衡中两厂商的产量分别为：1250q q ==。