海南大学：《西方经济学》课程试卷解答（微观经济学）2008-2009微观经济学期终考试（A）答案.doc_大学文库

海南大学2007-08学年度第1学期《微观经济学》答案(A卷) 一、Please ex plain the following terms:(每题5分，共50分) 1Zero econm profit Afirm is earning return on its investment-ie,that it is doing as well as it could by investing its money. 2 Welfare economies Normative evaluation of markets and economic policy Welfare effeets Gains and losses caused by government intervention in the market 3 User cost of capital (Page 215)Sum of the annual cost of owning and using a capital asset. equal to economic depreciation plus forgone interest. 4Two-part tariff Form of pricing in which consumers are charged both an entry and a usage fee- 5 Theory of the firm Explanation of how a firm makes cost-minimizing production decisions and hw with its oupu 6Theory of consumer behavior Description of how consumers allocate incomes among different goods and services to maximize their well-being. 7Tit-for-tat strategy Repeated-game strategy in which a player responds in kind to an opponent's previous play,cooperating with cooperative opponents and retaliating against uncooperative ones. 8 Transferable emissions permits Syste em of marketable pemits,allocatod among firms specifying the maximum level of emissions that can be generated 9Rent seeking Spending money in socially unproductive efforts to acquire,maintain,or exercise monopoly power. 10 Reservation price Maximum price that a customer is willing to pay for a good. 二、简答题：（共10分） 1.Medical research has shown the negative health effects of "secondhand"smoke Recent social trends point to growing intolerance of smoking in public areas.If you are a smoker and you wish to continue smoking despite tougher anti smoking laws,describe the effect of the following legislative proposals on your behavior. e programs,do you,the individual smoker,benefit? Does society benefit as a whole? Since smoking in public areas is similar to polluting the air,the programs proposed here are similar to those examined for air pollution.A bill to lower tar and nicotine levels is similar to an emissions standard, and a tax on cigarettes is similar to an

海南大学 2007-08 学年度第 1 学期《微观经济学》答案(A 卷) 一、Please explain the following terms：（每题 5 分，共 50 分） 1 Zero economic profit A firm is earning a normal return on its investment-i.e., that it is doing as well as it could by investing its money elsewhere. 2 Welfare economics Normative evaluation of markets and economic policy Welfare effects Gains and losses caused by government intervention in the market. 3 User cost of capital (Page 215) Sum of the annual cost of owning and using a capital asset, equal to economic depreciation plus forgone interest. 4 Two-part tariff Form of pricing in which consumers are charged both an entry and a usage fee. 5 Theory of the firm Explanation of how a firm makes cost-minimizing production decisions and how its cost varies with its output. 6 Theory of consumer behavior Description of how consumers allocate incomes among different goods and services to maximize their well-being. 7 Tit-for-tat strategy Repeated-game strategy in which a player responds in kind to an opponent’s previous play, cooperating with cooperative opponents and retaliating against uncooperative ones. 8 Transferable emissions permits System of marketable permits, allocat6d among firms, specifying the maximum level of emissions that can be generated. 9 Rent seeking Spending money in socially unproductive efforts to acquire, maintain, or exercise monopo1y power. 10 Reservation price Maximum price that a customer is wi1ling to pay for a good. 二、简答题：（共 10 分） 1. Medical research has shown the negative health effects of “secondhand” smoke. Recent social trends point to growing intolerance of smoking in public areas. If you are a smoker and you wish to continue smoking despite tougher anti smoking laws, describe the effect of the following legislative proposals on your behavior. As a result of these programs, do you, the individual smoker, benefit? Does society benefit as a whole? Since smoking in public areas is similar to polluting the air, the programs proposed here are similar to those examined for air pollution. A bill to lower tar and nicotine levels is similar to an emissions standard, and a tax on cigarettes is similar to an

emisions eRegiring mokin assuming that the permits would not be transferable. these programs is being forced to interalize the externality of "second-hand"smoke and will be worse off.Society will be better off if the benefits of a particular proposal outweigh the cost of implementing that proposal.Unfortunately,the benefits of reducing second-hand smoke are uncertain,and assessing those benefits iscos a.A bill is proposed that would lower tar and nicotine levels in all cigarettes. The smoker will most likely try to maintain a constant level of consumption of nicotine,and will increase his or her consumption of cigarettes.Society may not beefit from this pan if the total amount of tar and nictine same. b.A tax is levied on each pack of cigarettes sold. Smokers might,pipes,or might start rolling theirown cigarettes.The demand for cigarettes.Again,it is questionable whether society will benefit. c.Smokers would be required to carry government issued smoking permits at all times Smoking permits would effectively transfer property rightsto cleanair from smoker to non-smokers.The main obstacle to society benefiting from such a proposal would be the high cost of enforcing a smoking permits system.In addition,the cost of the permit raises the effective price of the cigarettes and the resulting affect on quantity smoked will depend on the elasticity of demand 三、Calculation:(每题20分，共40分) a.Suppose both firms have entered the industry.What is the joint profit-maximizinglevel ofoutput?How much will each firm produce?How If the market,and they ollude,they will face a marginl revenue cuve with twice the slope of the demand curve: MR=50.10Q ower than that of Firm 2)to determine the profit-maximizing quantity, 50·10Q=10,0rQ=4. Substituting =4 into the demand function to determine price: P=50-5*4=$30. The question now is how the firms will divide the total output of 4 among themselves Since the two firms have different cost functions,it will not be optimal for them to split the output evenly between them.The profit maximizing solution is for firm 1 to produce all of the output so that the profitfor Firm 1 will be: 1=(0④(20+(104)=s60

emissions fee. Requiring a smoking permit is similar to a system of emissions permits, assuming that the permits would not be transferable. The individual smoker in all of these programs is being forced to internalize the externality of “second -hand” smoke and will be worse off. Society will be better off if the benefits of a particular proposal outweigh the cost of implementing that proposal. Unfortunately, the benefits of reducing second-hand smoke are uncertain, and assessing those benefits is costly. a. A bill is proposed that would lower tar and nicotine levels in all cigarettes. The smoker will most likely try to maintain a constant level of consumption of nicotine, and will increase his or her consumption of cigarettes. Society may not benefit from this plan if the total amount of tar and nicotine released into the air is the same. b. A tax is levied on each pack of cigarettes sold. Smokers might turn to cigars, pipes, or might start rolling their own cigarettes. The extent of the effect of a tax on cigarette consumption depends on the elasticity of demand for cigarettes. Again, it is questionable whether society will benefit. c. Smokers would be required to carry government issued smoking permits at all times. Smoking permits would effectively transfer property rights to clean air from smokers to non-smokers. The main obstacle to society benefiting from such a proposal would be the high cost of enforcing a smoking permits system. In addition, the cost of the permit raises the effective price of the cigarettes and the resulting affect on quantity smoked will depend on the elasticity of demand. 三、Calculation：（每题 20 分，共 40 分） 1. Consider two firms facing the demand curve P = 50 - 5Q, where Q = Q1 + Q2 . The firms’ cost functions are C1 (Q1 ) = 20 + 10Q1 and C2 (Q2 ) = 10 + 12Q2 . a.Suppose both firms have entered the industry. What is the joint profit-maximizing level of output? How much will each firm produce? How would your answer change if the firms have not yet entered the industry? If both firms enter the market, and they collude, they will face a marginal revenue curve with twice the slope of the demand curve: MR = 50 - 10Q. Setting marginal revenue equal to marginal cost (the marginal cost of Firm 1, since it is lower than that of Firm 2) to determine the profit-maximizing quantity, Q: 50 - 10Q = 10, or Q = 4. Substituting Q = 4 into the demand function to determine price: P = 50 – 5*4 = $30. The question now is how the firms will divide the total output of 4 among themselves. Since the two firms have different cost functions, it will not be optimal for them to split the output evenly between them. The profit maximizing solution is for firm 1 to produce all of the output so that the profit for Firm 1 will be: 1 = (30)(4) - (20 + (10)(4)) = $60

The profit for Firm 2 will be: 2 = (30)(0) - (10 + (12)(0)) = -$10. Total industry profit will be: T = 1 + 2 = 60 - 10 = $50. If they split the output evenly between them then total profit would be $46 ($20 for firm 1 and $26 for firm 2). If firm 2 preferred to earn a profit of $26 as opposed to $25 then firm 1 could give $1 to firm 2 and it would still have profit of $24, which is higher than the $20 it would earn if they split output. Note that if firm 2 supplied all the output then it would set marginal revenue equal to its marginal cost or 12 and earn a profit of 62.2. In this case, firm 1 would earn a profit of –20, so that total industry profit would be 42.2. If Firm 1 were the only entrant, its profits would be $60 and Firm 2’s would be 0. If Firm 2 were the only entrant, then it would equate marginal revenue with its marginal cost to determine its profit-maximizing quantity: 50 - 10Q2 = 12, or Q2 = 3.8. Substituting Q2 into the demand equation to determine price: P = 50 – 5*3.8 = $31. The profits for Firm 2 will be: 2 = (31)(3.8) - (10 + (12)(3.8)) = $62.20. b.What is each firm’s equilibrium output and profit if they behave noncooperatively? Use the Cournot model. Draw the firms’ reaction curves and show the equilibrium. In the Cournot model, Firm 1 takes Firm 2’s output as given and maximizes profits. The profit function derived in 2.a becomes 1 = (50 - 5Q1 - 5Q2 )Q1 - (20 + 10Q1 ), or   = 40Q1 − 5Q1 2 − 5Q1Q2 − 20. Setting the derivative of the profit function with respect to Q1 to zero, we find Firm 1’s reaction function:   Q1 = 40 −10Q1 - 5Q2 =0, or Q1 = 4 - Q2 2     . Similarly, Firm 2’s reaction function is  Q2 = 3.8 − Q1 2     . To find the Cournot equilibrium, we substitute Firm 2’s reaction function into Firm 1’s reaction function:  Q1 = 4 − 1 2     3.8 − Q1 2     , or Q1 = 2.8. Substituting this value for Q1 into the reaction function for Firm 2, we find Q2 = 2.4. Substituting the values for Q1 and Q2 into the demand function to determine the equilibrium price: P = 50 – 5(2.8+2.4) = $24. The profits for Firms 1 and 2 are equal to 1 = (24)(2.8) - (20 + (10)(2.8)) = 19.20 and 2 = (24)(2.4) - (10 + (12)(2.4)) = 18.80

c. How much should Firm 1 be willing to pay to purchase Firm 2 if collusion is illegal but the takeover is not? In order to determine how much Firm 1 will be willing to pay to purchase Firm 2, we must compare Firm 1’s profits in the monopoly situation versus those in an oligopoly. The difference between the two will be what Firm 1 is willing to pay for Firm 2. From part a, profit of firm 1 when it set marginal revenue equal to its marginal cost was $60. This is what the firm would earn if it was a monopolist. From part b, profit was $19.20 for firm 1. Firm 1 would therefore be willing to pay up to $40.80 for firm 2. 2. In a market for dry cleaning, the inverse market demand function is given by  P = 100− Q and the (private) marginal cost of production for the aggregation of all dry cleaning firms is given by  MC =10 + Q . Finally, the pollution generated by the dry cleaning process creates external damages given by the marginal external cost curve  MEC = Q. a Calculate the output and price of dry cleaning if it is produced under competitive conditions absent regulation. To find the answer, set price equal to marginal cost: 100-Q=10+Q, Q=45, and P=55. b Determine the socially efficient price and output of dry cleaning. To find the answer here, we must first calculate the marginal social cost (MSC), which is equal to the marginal external cost plus the private marginal cost. Next, set MSC equal to the market demand function to solve for price and quantity. When all costs are included, the quantity produced will fall and the price will rise: MSC=MC+MEC=10+2Q=100-Q, Q=30, and P=70. c Determine the tax that would result in a competitive market producing the socially efficient output. If there is a unit tax, then the new marginal private cost function is MC’=10+Q+tQ. If we now set this new marginal cost function equal to the price of 70 and substitute in 30 for the quantity, we can solve for t: 10+Q+tQ=70 Q(1+t)=60 1+t=2 t=1. The tax should be $1 per unit output. Note that with the tax equal to 1, the new private cost function is the same as the marginal social cost function