中级微观经济学范里安版本2-5章习题

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范里安-中级微观经济学-课件-第5章

最优选择－折拗解
x2
45o
x1
.
8
最优选择－角点解（边界解）
x2
x1
.
9
最优选择－角点解（边界解）
x2
角点解处其中一种商品的最优消费量等于零，且边际替代率（一般）不等于商品价格比。
x1* x1
.
10
最优选择
内点解
预算线与无差异曲线在“内点”相切
折拗解角点解
预算线与无差异曲线的“折拗点”在 “内点”相交
x2
在此例中，所得税优于从量税
x2*
I1
I2
I3
x1* .
x1
32
• 但要注意：下述情况下所得税优于从量税的结论并不必然成立。
➢ 消费者本来就不购买任何的商品1；
➢ 所得税可能挫伤消费者赚取收入的热情，以致课征所得税导致消费者可支配（税后）收入的大幅下降；
➢ 通过市场供给和需求的相互作用，消费者可以将从量税的一部分税收负担转移给厂商。
第5章选择
.
1
第5章选择
• 学习目的：掌握消费者最优选择的条件和性质。
• 主要内容：1、“最优选择”的条件及其含义； 2、消费者需求； 3、若干例子； 4、理论运用：税收类型的选择
.
2
1、“最优选择”的条件及其含义
（1）消费者的行为模式假说：消费者从他们的预算集中选择最偏好的消费束；
（2）最优选择的条件
（4）离散商品
（5）非凸偏好（角点解）
（6）柯布－道格拉斯偏好（内点解）
.
22
完全替代品的情况（角点解）
x2
MRS = -1
x
* 1
m p1
x

中级微观经济学-范里安版本

如果允许自由处置，则称生产技术具有单调性：单调性：如果x 在 V（y）中，并且 x' x 则 x ' 也在 V（y）中。思考自由处置的现实背景：处置或储藏不需要成本，至少不能影响到原有技术的施行。
• 凸技术思想：我们想要生产“大”量的产出，并且可以复制“小”的生产过程
定义：凸性如果x 和 x ' 都在V（y）中，那么，对 ' tx (1 t) x 所有0≤t≤1的t 而言，在V（y）中。那就是，V（y）是一个凸集。
• 取极限形式后，写成
TRS d x2 / x1 x2 / x1 dTRS
经济含义：可以通过厂商追求成本最小化的一阶条件来重新审视替代弹性的含义。
• 使用对数微商，可以重新写为 d ln x2 / x1
d ln | TRS |
例：柯布道格拉斯生产函数的替代弹性
a x2 TRS 1 a x1 x2 1 a TRS x1 a
x2 1 a ln ln ln | TRS | x1 a
d ln x2 / x1 1 d ln | TRS |
• 规模报酬前面“复制”生产过程的例子实际上是“按比例增加”投入，那么规模报酬不变意味着：下列任何一个条件被满足，即称为规模报酬不变 1．对所有非负t；y在Y 中意味着ty 在Y 中 2．x在V（y）中意味着tx在V（y）中，对所有t≥0 ？ 3． f (tx) tf(x) ，对于所有t≥0。即生产函数f(x)是一次齐次的。那么，何时规模报酬不变会被违反？
V（y） = x在R n -x Y中 +中：（y，）在
等产量线：等产量线给出所有刚好生产y 单位产出的投入束。
，， Q（y） = x在R n 中： x 在 V(y) 中并且 x 不在 V （ y ）中， y >y +

中级微观经济学 1—5,17,18

比较静态学：
当市场的各个方面发生变化时，住房价格会有什么变动。这种做法就是比较静态学。（两个“静态”均衡的比较）
简单的情况：假设住房的供给增加了简单的情况：假设住房的供给增加了…… 假设住房的供给减少了…… 假设住房的供给减少了更为复杂也更为有趣的例子：更为复杂也更为有趣的例子：假设有一个房地产开发商决定把一些住房改成个人所有的公那么其余住房的价格会有什么变动呢？寓，那么其余住房的价格会有什么变动呢？另一个令人奇怪的比较静态学分析的例子：另一个令人奇怪的比较静态学分析的例子：对住房征税所产生的影响
需求曲线
某人愿意支付的最高价格通常被认为是他或她。（保留价格是某人愿意接受的、保留价格是某人愿意接受的的保留价格。（保留价格是某人愿意接受的、并且
购买商品的最高价格。）购买商品的最高价格。）
供给曲线
许多独立的房东都想以市场能接受的最高价格出租他们的住房：出租他们的住房：竞争市场
短期：短期：住房的供给固定在某一个预先决定的水平
什么方法最好？什么方法最好？
首先得给“最好” 首先得给“最好”下定义
看有关人员的经济地位 ——对房东来说对房东来说 ——对租赁者来说对租赁者来说
——对所有参与者来说对所有参与者来说
帕累托效率（经济效率）帕累托效率（经济效率）
帕累托效率”可以这样来定义： “帕累托效率”可以这样来定义：如果没有一个人可以在不使任何其他人的处境变差的前提下而使自己的处境变得更好，任何其他人的处境变差的前提下而使自己的处境变得更好，那么，帕累托最优” 那么，这种状态就是 “ 帕累托最优” ，它被认为是一帕累托效种最有效率的资源配置状态，所以也叫 “ 帕累托效能够朝着这个帕累托最优状态方向前进的行为，率”。能够朝着这个帕累托最优状态方向前进的行为，叫做 “ 帕累托改进” ，而只要存在“ 帕累托改进” 的余帕累托改进” 而只要存在“ 帕累托改进” 那么，帕累托效率”就还没有达到。地，那么，“帕累托效率”就还没有达到。

中级微观经济学范里安课后答案

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】

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 。

范里安中级微观经济学第八版习题

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。

微观经济学第五章(范里安)

二、消费者需求
需求函数是将最优选择的需求数量与不同的价格和收入值联系在一起的函数。
1.完全替代
X1=
m/p1 介于0与m/p1之间
0
若p1<p2 若p1=p2 若p1p2
the Perfect Substitutes Case
x2 MRS = -1
x1
the Perfect Substitutes Case
xRational Constrained Choice
2
(x1*,x2*) is the most
preferred affordable
bundle.
x2*
x1*
x1
Rational Constrained Choice
4.结论：(x1*,x2*) satisfies two conditions:
x1
Examples of Corner Solutions -- the Non-Convex Preferences Case
x2
Notice that the “tangency solution” is not the most preferred affordable
bundle.
The most preferred affordable bundle
Then
MU1
U x1
ax1a1xb2
MU2
U x2
bx1axb2 1
x2
U(x1,x2) = min{ax1,x2}
x2 = ax1 x1
the Perfect Complements Case
x2
U(x1,x2) = min{ax1,x2}
The most preferred afforable bundle

第2章预算约束(含习题解答)- 范里安微观经济学现代观点(中文7版)-东南大学曹乾

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)。

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Intermediate Microeconomics,Spring2016Instructor:Siwei Chen,Yang YangAssignment1(due date:March8/March10)a.Assignments should be submitted at the beginning of next week’s te submissions will not be accepted.b.Discussion with classmates is encouraged.But you should write up answers independently.c.If the case of identical answers is found,all the students involved in verbatim copying will receive a score of zero.Budget Constraint1.Suppose that Ming has$60to spend on either CDs or video rentals.For each of the situations described below,draw Ming’s budget line.Put“CDs”on the x-axis,and“video rentals”on the y-axis.Provide coordinates of all special points on the graph.(Treat CDs and video rentals as CONTINUOUS goods,which can be con-sumed in non-integer amounts.)(a)CDs are$10each and video rentals are$6each.(b)The prices are the same as in(a).The government imposes a20%value tax on CDs.(c)Video-rentals are$6each.CDs are$10each for theﬁrst three,and$6each for additional ones.(For example,the cost for two CDs is10*2=20;The cost forﬁve CDs is10*3+6*2=$42.)(d)The prices are the same as in(a).However,there is an on-going promotion of CDs,a bundle of four CDs for$30.(For example,the cost ofﬁve CDs is30+10=40;The cost of eight CDs is 30+30=60.)(e)The prices are the same as in(a).However,there is an on-going promotion of video rentals. Ming can buy a member card for$36,which allows him to rent up to10videos.(f)The prices are the same as in(a).The government imposes a$30lump-sum tax on Ming,but compensates him with a member card which allows him to rent up to10videos.(g)The prices are the same as in(a).The government imposes a50%value subsidy on CDs. However,Ming can buy at most8CDs.2.Jenny wants to intake royal jelly and pollen for health,and she has$60to spend on drinksevery month.There are two types of drinks on the market containing royal jelly and pollen, Popsi and Cela,each with a different formula.Each100ml of Popsi contains10ml of royal jelly and20g of pollen.Each100ml of Cela contains20ml of royal jelly and25g of pollen.The prices of Popsi and Cela are,respectively,$10and$15for each100ml.(a)Put the amount of royal jelly on the x-axis and the amount of pollen on the y-axis.Draw Jenny’s two extreme consumption bundles on the graph when she spends all the budget on Popsi,or Cela.(b)What is Jenny’s budget set?Mark it out by shadow on the graph you’ve plotted in(a).Preferences3.Prof.Goodheart gives two midterms in his communications class.He only uses the higher of the two scores that a student gets on the midterms when calculating the course grade.Nancy is taking Prof.Goodheart’s course and wants to maximize her grade.Let x1be her score on the ﬁrst midterm,and x2be her score on the second midterm.(a)Which combination would Nancy prefer,x1=30and x2=70,or x1=60and x2=60?(b)Draw the indifference curve going through(30,70),and the indifference curve going through (60,60).(c)Does Nancy have monotonic preferences?Does Nancy have convex preferences?(d)Suppose that Prof.Goodheart changes his policy.He uses the lower of the two scores that a student gets on the midterms when calculating the course grade.Re-answer parts(a)-(c). (e)Suppose that Prof.Goodheart uses the average of the two scores that a student gets on the midterms when calculating the course grade.Re-answer parts(a)-(c).4.Consider the following two goods:concerts and movies.Draw indifference curves that rep-resent the preferences of each of the following people.Put“concerts per month”on the x-axis, and“movies per month”on the y-axis.For each graph,label the direction of increasing welfare with an arrow.(a)YoYo Ma likes concerts,but does not care whether or not he watches movies.(b)Ruth like movies,but dislikes concerts.(c)Carlos dislikes both movies and concerts.He dislikes each additional movie more,as he watches more movies.He dislikes each concert the same,no matter how many he goes to.(d)Sanjay also dislikes both movies and concerts.He dislikes each concert the same,no matter how many concerts he goes to.However,unlike Carlos,he dislikes each additional movie less, as he watches more movies.(e)Marie likes concerts up to three per month,and then starts to dislike extra ones.However, she likes movies no matter how many she watches.(f)Andrea likes it best when she watches three movies and goes to two concerts each month. If she deviates from this optimal consumption bundle,she would be dissatisﬁed.The further away she deviates from the optimal bundle,the more dissatisﬁed she is.Utility5.Calculate the marginal utility of x1,the marginal utility of x2,and the marginal rate of sub-stitution,for the following utility functions:(a)2x1+3x2(b)ln x1+x2(c)x a1x b2(d)(x1+2)(x2+1)6.Assume that t>0.Is each of the following functions a monotonic transformation?(a)f(t)=t2(b)f(t)=t−2(c)f(t)=(ln t)27.Apply the three transformations from Question6to the utility function u(x1,x2)=x a1x b2. Write down the three new utility functions.Calculate the marginal rate of substitution for each of them.Do they represent the same preference relation as u(x1,x2)=x a1x b2?。