中级微观经济学第八次作业及解答 最终版

第一部分 消费者理论1. 当11xx 时，加数量税t,画出预算集并写出预算线预算集：).....(. (1)12211x x m x p x p).........(..........)(1112211x x x t m x p x t p2. 如果同样多的钱可以买（4，6）或（12，2），写出预算线。

mx p x p 2211 则有mp p 2164，mp p 21212不妨假设12 p ，则可解得：8,211 m p 。

预算线为82121 x x 3．(1)0.4100x y(2)0.2100.............300.4106.............30x y if x x y if x(3)0.4106x y4. 证明：设两条无差异曲线对应的效用分别为21,uu ，由曲线的单调性假设，若21uu ，则实为一条曲线。

若21uu ，假设两曲线相交，设交点为x，则21)(,)(ux u u x u ，可推出21uu ，存在矛盾，不可能相交。

5. -5(把一元纸币放在纵轴上)或者-1/5(把一元纸币放在横轴上),6. 中性商品是指消费者不关心它的多少有无的商品商品2 如果也是中性商品那么该题就无所谓无差异曲线,也无所谓边际替代率了. 商品2如果不是中性商品:边际替代率是0(把中性商品放在横轴上)或者 (把中性商品放在纵轴上)7. (1)x1 is indefinitely the substitution of x2, and five units of x1 can bring the same utility as that one unit of x2 can do. With the most simple form of the utilityfunction,125u x x x , and assume that the prices of those two goods are p1 and p2 respectively and the total wealth of the consumer is m, the problem can be writtenas121112max ,..u x xst p x p x m③ Because 5p1=p2, any bundle 12,x x which satisfies the budget constraint, is thesolution of such problem.(2) A cup of coffee is absolutely the complement of two spoons of sugar. Let x1 and x2 represent these two kinds of goods, then we can write the utility function as12121,min ,2u x x x xThe problem of the consumer is121112max ,..u x xst p x p x mAny solution should satisfies the rule that 1212x x , and the budget constraint.So replace x1 with (1/2)(x2) in the budget constraint and we can get 1122mx p p,and 21222mx p p.8. (1) Because the preference is Cobb-Douglas utility, we can simplify thecomputation by the formula that the standardized parameter of one commodity means its share of total expenditure.So directly, the answer is 1123m x p , 213mx p.（详细方法见8(2)）. （2）库恩-塔克定理。

一、名词辨析1.规范分析与实证分析；实证分析方法：实证分析不涉及价值判断，只讲经济运行的内在规律，也就是回答“是什么”的问题；实证分析方法的一个基本特征它提出的问题是可以测试真伪的，如果一个命题站得住脚，它必须符合逻辑并能接受经验数据的检验。

规范分析方法：规范分析以价值判断为基础，以某种标准为分析处理经济问题的出发点，回答经济现象“应当是什么”以及“应当如何解决”的问题，其命题无法证明真伪。

2.无差异曲线与等产量线；无差异曲线是指这样一条曲线，尽管它上面的每一点所代表的商品组合是不同的，但消费者从中得到的满足程度却是相同的。

等产量线表示曲线上每一点的产量都相等，是由生产出同一产量的不同投入品组合所形成的曲线。

3.希克斯补偿与斯卢茨基补偿;希克斯补偿是指当商品价格发生变化后，要维持原有效用水平所需补偿的货币数量。

斯卢茨基补偿是指当商品价格发生变化后，要维持原有消费水平所需补偿的货币数量。

4.边际替代率与边际技术替代率；边际替代率是指，消费者在增加额外一单位商品X之后，若要保持满足水平不变而必须放弃的商品Y的数量。

边际替代率就等于无差异曲线在该点的斜率的绝对值。

边际技术替代率是指，当只有一种投入品可变时，要增加产量，企业必须投入更多的另一种投入品；当两种投入品都可变时，企业往往会考虑用一种投入品来替代另一种投入品。

等产量线斜率的绝对值就是两种投入品的边际技术替代率。

5.边际产出与边际收益产出边际产出，就是指在其他生产资源的投入量不变的条件下,由于增加某种生产资源一个单位的投入,相应增加的产出量。

当产出以产量表示时,即为边际产量;当产出以产值表示时,即为边际产值。

边际收益产出是指，额外单位劳动给企业带来的额外收益是劳动的边际产品与产品的边际收益的乘积。

6.显性成本与隐性成本；显性成本：是指厂商在生产要素市场上购买或租用所需要的生产要素的实际支出；隐性成本：是指厂商本身所拥有的且被用于该企业生产过程的那些生产要素的总价格。

第8章课后题答案一、基本概念市场失灵：是指市场机制不能有效地发挥配置稀缺性资源的作用，难以实现帕累托效率的状况。

信息不对称：即经济活动中，一方当事人比另一方拥有更多的信息，信息不对称的存在将造成市场机制不能有效率发挥作用，即市场失灵。

外部效应：是指一种活动的收益或成本，并不完全由活动的当事人来分享或承担。

公共物品：既具有非竞争性又具有非排他性特征，能被大家共同消费，一个人使用并不减少另一个人对它的使用。

寻租：企业为获得或维护其垄断地位而花费大量资源用于非生产性活动上。

搭便车：是指得到一种物品的利益但避开为此付费的行为。

公地的悲剧：当资源或财产有许多拥有者，他们每一个人都有权使用资源，但没有人有权阻止他人使用，由此导致资源的过度使用，即为“公地悲剧”。

效率工资：就是企业或其他组织支付给员工的比市场平均水平高得多的工资促使员工努力工作的一种激励与薪酬制度。

逆向选择：信息不对称所造成市场资源配置扭曲的现象。

道德风险：具有信息优势的一方在最大限度增进自己效用时作出不利于处于信息劣势一方的行为，比如欺诈、违约、投机取巧等这些“不恰当”或“不道德”的行为，这些行为在西方叫“道德风险”。

二、分析简答1、举例并作图说明垄断的社会成本。

垄断造成社会福利的无谓损失，这种无谓损失就是垄断的社会成本。

我们可以通过比较完全竞争和垄断情况下的消费者剩余和生产者剩余来理解垄断的社会成本，(假设竞争的市场和垄断者有相同的成本曲线)。

如下图所示，给出了垄断者的平均收益曲线和边际收益曲线以及边际成本曲线。

为了使利润最P和大化，厂商在边际收益等于边际成本之处生产，因此均衡价格和产量分别是mm Q 。

在一个竞争的市场中，价格必须等于边际成本，由平均收益（即需求）曲线与边际成本曲线的交点决定了竞争价格（c P ）和产量（c Q ）。

现在让我们看一下当竞争价格（c P ）和产量（c Q ）移动到垄断价格（m P ）和产量（m Q ）时，两个剩余是如何变化的。

第八章生产要素价格决定的需求方面1.说明生产要素理论在微观经济学中的地位.解答：要点如下：第一，从商品的角度来看，微观经济学可以分为两个部分，即关于“产品”的理论和关于“要素”的理论.前者讨论产品的价格和数量的决定，后者讨论要素的价格和数量的决定.第二，产品的理论和要素的理论是相互联系的.特别是，产品理论离不开要素理论，否则就不完全.这是因为，首先，产品理论在讨论产品的需求曲线时，假定了消费者的收入水平为既定，但并未说明收入是如何决定的，其次，在推导产品的供给曲线时，假定了生产要素的价格为既定，但并未说明要素的价格是如何决定的.这两点都与要素理论有关.因此，要素理论可以看成是产品理论的自然的延伸和发展. 在西方经济学中，产品理论通常被看成是“价值”理论，要素理论通常被看成是“分配”理论.产品理论加上要素理论，或者，价值理论加上分配理论，构成了整个微观经济学的一个相对完整的体系.2.试述厂商的要素使用原则.解答：要点如下：第一，厂商在使用要素时同样遵循利润最大化原则，即要求使用要素的“边际成本”和“边际收益”相等.第二，在一般情况下，场上使用要素的边际收益是“边际收益产品”（要素的边际产品和产品的边际收益的乘积），边际成本是“边际要素成本”.因此，一般场上使用要素的原则是：边际收益产品等于边际要素成本.第三，在完全竞争条件下，边际收益产品等于“边际产品价值”（要素的边际产品和产品价格的乘积），而边际要素成本等于“要素价格”.于是，完全竞争厂商使用要素的原则是：边际产品价值等于要素价格.3、要素使用原则与利润最大化产量原则有何关系？解答：要点如下：第一，在西方经济学中，利润最大化被假定为是任何厂商的任何活动都必须遵守的原则.因此，无论是产量的决定还是要素使用量的决定，遵守的都是同一个利润最大化原则.该原则意味着，任何厂商的任何活动的“边际收益”和“边际成本”必须相等.第二，在不同的场合，边际收益和边际成本的具体内容并不相同.例如，在产量的决定问题上，边际收益和边际成本是指增加一单位产量增加的收益和成本，而在要素使用量的决定问题上，边际收益和边际成本则是指增加使用一单位要素增加的收益和成本.第三，增加使用一单位要素所增加的收益叫“边际收益产品”，它等于要素的边际产品和产品的边际收益的乘积.因此，增加使用要素的边际收益包括了产品的边际收益.另一方面，要素的边际成本与产品的边际成本的关系则比较复杂.这是因为，要素的边际成本通常仅指增加使用某种特定要素如劳动所引起的成本变化，而产品的边际成本则与多种要素（如劳动和资本）的共同变化有关——产品是由多种要素共同生产出来的.4、在什么情况下，要素的需求曲线不存在？解答：要点如下：第一，要素需求曲线意味着，在一定范围内，对于每一个要素的价格，都有一个唯一的要素需求量与之对应.第二，如果在要素市场上，市场的买方属于完全竞争（卖方则既可以是完全竞争，也可以是不完全竞争），则给定一个要素价格，就有一个唯一的要素需求量与之对应，即存在要素的需求曲线.第三，如果在要素市场上，市场的买方属于不完全竞争（如垄断），则会出现如下情况：对于同一个要素价格，可能会有多个不同的要素需求量与之对应.在这种情况下，就不存在一条确定的要素需求曲线.5、试述厂商及市场在完全竞争和垄断、行业调整存在和不存在等各种情况下的要素需求曲线.解答：要点如下：第一，在完全竞争条件下，厂商对要素的需求曲线向右下方倾斜，即随着要素价格的下降，厂商对要素的需求量将增加.第二，如果不考虑厂商所在行业中其他厂商的调整，则该厂商的要素需求曲线就恰好与其边际产品价值曲线重合.第三，如果考虑厂商所在行业中其他厂商的调整，则该厂商的要素需求曲线将不再与边际产品价值曲线重合.这是因为，随着要素价格的变化，如果整个行业所有厂商都调整自己的要素使用量，从而都改变自己的产量的话，产品的市场价格就会发生变化.产品价格的变化会再反过来使每一个厂商的边际产品价值曲线发生变化.于是，厂商的要素需求曲线将不再等于其边际产品价值曲线.在这种情况下，厂商的要素需求曲线叫做“行业调整曲线”.行业调整曲线仍然向右下方倾斜，但比边际产品价值曲线要陡峭一些.第四，在完全竞争条件下，市场的要素需求曲线等于所有厂商的要素需求曲线（行业调整曲线）的水平相加.第五，不完全竞争的情况比较复杂.在不完全竞争要素市场中，卖方垄断厂商的要素需求曲线向右下方倾斜，即随着要素价格的下降，厂商对要素的需求量将增加，而且，它还与边际收益产品曲线恰好重合. 第六，在不完全竞争要素市场中，如果所有厂商均是卖方垄断者，则它们的要素需求曲线就等于各自的边际收益产品曲线.于是，市场的要素需求曲线就是所有这些厂商的边际收益产品曲线的水平相加. 第七，如果在不完全竞争要素市场中，并非所有厂商均是卖方垄断者，则它们的要素需求曲线就是行业调整曲线.于是，市场的要素需求曲线就是所有这些厂商的行业调整曲线的水平相加.买方垄断厂商的要素需求曲线不存在.6、设一厂商使用的可变要素为劳动L，其生产函数为：Q=-0.01L3+L2+38L其中，Q为每日产量，L时每日投入的劳动小时数，所有市场（劳动市场及产品市场）都是完全竞争的，单位产品价格为0.10美元，小时工资为5美元，厂商要求利润最大化.问厂商每天要雇用说少小时劳动？解答：要点如下：已知工资W=5.根据生产函数及产品价格P=0.10，可求得劳动的边际产品价值如下： VMP L =P ×MPP L =P ×dLdQ=0.10×()3801.0(23'++-L L ) =0.01×(-0.03L 2+2L+38)第三，完全竞争厂商的利润最大化要求边际产品价值等于工资，即： 5=0.10×(-0.03L 2+2L+38) 或 0.03L 2-2L+12 第四，解之得： L 1=20/3 L 2=60.第五，当L 1=20/3时，利润为最小（因为6.1=dLdMPP L>0），故略去. 第六，当L 2=60时，利润为最大（6.1-=dLdMPP L＜0）.故厂商每天要雇佣60小时的劳动.7、已知劳动是唯一的可变要素，生产函数为Q=A+10L-5L 2，产品市场是完全竞争的，劳动价格为W ，试说明： （a ）厂商对劳动的需求函数.(b)厂商对劳动的需求量与工资反方向变化. (c)厂商对劳动的需求量与产品价格同方向变化. 解答：（a ）因产品市场为完全竞争市场，根据 W=VMP=P ×MPP L =P ×dLdQ即 W=P ×（10-10L ）=10P-10PL 得厂商对劳动的需求函数为：L=PW101-（b ）因 PW L 101-=∂∂ ＜0 ，故厂商对劳动的需求量与工资反方向变化.（c ）因 210P PP L =∂∂ >0 ，故厂商对劳动的需求量与产品价格同方向变化.8、某完全竞争厂商雇用一个劳动日的价格为10元，其生产情况如下表所示.当产品价格为5元，它应雇用多少个劳动日？解答：由题意可计算得下表：由表中可以看到，当L=7时，边际产品价值与工资恰好相等，均等于10.故厂商应雇佣7个劳动日.9、某产品和要素市场上的完全垄断者的生产函数为Q=4L.如果产品的需求函数为Q=100-P ，工人的劳动供给函数为L=0.5W-20，则为了谋求最大利润，该厂商应当生产多少产量？在该产量下，L ，W ，P 各等于多少？解答：由Q=100-P 即P=100-Q 及Q=4L 得： TR=PQ=（100-Q ）×Q=（100-4L ）×4L=400L-16L 2dLdTRMRP L ==400-32L 由L=0.5W-20即W=2（L+20）得： TC=WL=2（L+20）L=2L 2+40L MFC L =dLdTC=4L+40 利润最大化要求MRP L =MFC L ，即400-32L=4L+40 于是L=10 Q=4L=4×10=40W=2（20+L ）=2（20+10）=60 P=100-Q=100-40=6010、假定一垄断厂商仅使用劳动L 去生产产品.产品按竞争市场中的固定价格2出售.生产函数为q=6L+3L 2-0.02L 3，劳动供函数为W=60+3L.求利润最大化时的L ，q ，W. 解答：由q=6L+3L 2-0.02L 3得：dLdqMPP L ==6+6L-0.06L 2 于是VMP L=P×MPP L=2(6+6L-0.06L2)=12+12L-0.12L2由C L=WL=60L+3L2，得MFC L=60+6L根据VMP L=MFC L有：12+12L-0.12L2=60+6L0.12L2-6L+48=0得L1=10（舍去），L2=40于是，当利润最大化时有：L=40q=6×40+3×402-0.02×403=3760W=60+3×40=180。

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。

1章答案一、单项选择题1经济学最好的定义是对（）的研究。

a．社会如何管理其稀缺资源b．如何以最盈利的方式经营企业c．如何预测通货膨胀、失业和股票价格d．政府如何可以制止不受约束的利己所带来的危害【答案】a【解析】社会拥有的资源是有限的，因此不能生产人们希望拥有的所有物品与服务。

由于资源是稀缺的，社会资源的管理就尤为重要。

经济学研究社会如何管理自己的稀缺资源，经济学家还研究人们如何相互影响，分析影响整个经济的力量和趋势。

2你去看一场电影的机会成本是（）。

a．门票的价格b．门票的价格加上你在电影院购买汽水和爆米花的费用c．去看电影所需要的所有现金支出加上你的时间的价值d．零，只要你享受了电影并认为你为它付出的时间和金钱是值得的【答案】c【解析】机会成本是为了得到某种东西所必须放弃的东西。

看电影的机会成本包括：①去看电影所需要的所有现金支出，即门票的价格、购买汽水和爆米花的费用；②看电影的时间价值，即当把时间用于看电影时，就不能把这段时间用于工作，为此而不得不放弃的工作收入。

3边际变动（）。

a．对公共政策并不重要b．是逐步地改变现有计划c．使结果无效率d．并不影响激励【答案】b【解析】经济学家用边际变动这个术语来描述对现有行动计划的微小增量改变。

边际指边缘，边际变动是围绕所做的事的边缘的调整，即逐步地改变现有行动计划。

理性人通常通过比较边际收益与边际成本来做决策。

4亚当·斯密的看不见的手是指（）。

a．企业家以牺牲消费者为代价而获利的不易察觉而隐蔽的方法b．自由市场达到合意结果的能力（尽管市场参与者是利己的）c．政府通过管制使消费者获益的能力（即使消费者没有意识到这种管制）d．生产者或消费者在不受管制的市场上把成本加到无关旁观者身上的方法【答案】b【解析】经济学家亚当·斯密在其著作《国民财富的性质和原因的研究》中提出了全部经济学中最著名的观察结果：家庭和企业在市场上相互交易，他们仿佛被一只“看不见的手”所指引，并导致了合意的市场结果。

微观经济学第八版试题及答案一、选择题1. 需求定律表明，其他条件不变时，商品的价格上升，其需求量会：A. 增加B. 减少C. 不变D. 先增加后减少答案：B2. 在完全竞争市场中，长期均衡时，企业的经济利润为：A. 正B. 零C. 负D. 不确定答案：B3. 边际效用递减原理指的是：A. 随着消费量的增加，每增加一单位商品带来的额外满足感逐渐减少B. 随着消费量的增加，每增加一单位商品带来的额外满足感保持不变C. 随着消费量的增加，每增加一单位商品带来的额外满足感逐渐增加D. 以上都不是答案：A4. 价格弹性是指：A. 商品价格变化对需求量的影响程度B. 商品价格变化对供给量的影响程度C. 商品需求量变化对价格的影响程度D. 商品供给量变化对价格的影响程度答案：A5. 完全垄断市场中，垄断者可以通过调整：A. 产品价格B. 产品数量C. 产品品质D. 以上都是答案：D二、简答题1. 请简述价格歧视的三种类型及其特点。

答案：价格歧视是指同一商品或服务对不同消费者或在不同时间、地点收取不同价格的行为。

其三种类型包括：- 第一类价格歧视：针对每个消费者或每次交易单独定价。

- 第二类价格歧视：根据消费者购买量的不同，实行不同价格。

- 第三类价格歧视：在不同市场或消费者群体中实行不同价格。

2. 什么是外部性？请举例说明。

答案：外部性是指一个经济主体的行为对其他经济主体产生的非市场交易的影响。

分为正外部性和负外部性。

例如，一个工厂排放的废气可能对周围居民造成健康问题，这是负外部性；而一个大学的存在可能提高周边地区的文化水平和生活质量，这是正外部性。

三、计算题1. 假设某商品的需求函数为 Qd = 100 - 2P，供给函数为 Qs = 3P - 10。

求该商品的市场均衡价格和数量。

答案：市场均衡时，Qd = Qs。

将两个函数相等得到 100 - 2P =3P - 10，解得 P = 20。

将 P 值代入任一函数得到 Q = 100 - 2*20= 60。

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。

微观经济学第八章习题答案解答：第一，从商品的角度来看，微观经济学可以分为两个部分，即关于“产品”的理论和关于“要素”的理论。

前者讨论产品的价格和数量的决定，后者讨论要素的价格和数量的决定。

第二，产品的理论和要素的理论是相互联系的。

特别是，产品理论离不开要素理论，否则就不完全。

这是因为，首先，产品理论在讨论产品的需求曲线时，假定了消费者的收入水平既定，但并未说明收入水平是如何决定的；其次，在推导产品的供给曲线时，假定了生产要素的价格既定，但并未说明要素的价格是如何决定的。

这两点都与要素理论有关。

因此，要素理论可以看成是产品理论的自然延伸和发展。

第三，在西方经济学中，产品的理论通常被看成是“价值”理论，要素理论通常被看成是“分配”理论。

产品理论加上要素理论，或者，价值理论加上分配理论，构成了整个微观经济学的一个相对完整的体系。

2.试述完全竞争厂商的要素使用原则。

解答：第一，厂商在使用要素时同样遵循利润最大化原则，即要求使用要素的“边际成本”和“边际收益”相等。

第二，在完全竞争条件下，使用要素的边际收益等于“边际产品价值”(要素的边际产品和产品价格的乘积)，而使用要素的边际成本等于“要素价格”。

于是，完全竞争厂商使用要素的原则是：边际产品价值等于要素价格。

3.完全竞争厂商的要素使用原则与利润最大化产量原则有何关系？解答：从表面上看，完全竞争企业(实际上也包括其他企业)在生产过程中似乎有两个不同的决策要做：第一，购买多少要素？这是所谓的“要素需求”问题——使用多少要素才能够使利润达到最大？第二，生产多少产量？这是所谓的“产品供给”问题——生产多少产量才能够使利润达到最大？实际上，这两个问题是一回事。

这是因为在企业的要素需求和产品供给之间存在着一定的关系：如要减少对要素的需求，则产品供给常常就不得不减少；反之，如要增加对产品的供给，则要素的需求常常又不得不增加。

二者之间的关系就是所谓的生产函数：Q＝Q(L)。