课程名称︰个体经济学一 课程性质︰必修 课程教师︰江淳芳 开课学院：社会科学院 开课系所︰经济系 考试日期（年月日）︰2009/1/12 考试时限（分钟）：140 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 一选择题(20%) 1.The demand for tickets is given by D(p)=200,000-10,000p,where p is the price of tickets.If the price of tickets is$8,then the price elasticity of demand for tickets is a. -0.33 b. -1.33 c. -1 d. -2 e. -0.67 2.The demand for cable television hookus is Q=100-10p^0.5+2I^2,where P is price and I is per capita income.Cable TV is a. a normal good. b. a natural monopoly c. an inferior good d. a substitute good e. a complement good 3.Bernice's preferences can be represented by the utility funcion, U(x,y)=min{x,y}.She faces prices($2,$1),and her incomes is $12.If prices change to ($3,$1),the compensating variation a. equals the equivalent variations. b. is $2 greater than the equivalent variation. c. is $2 smaller than the equivalent variation. d. is $1 greater than the equivalent variation. e. There is not enough information to determine which variation is larger. 4.Sally is an expected utility maximizer with utility function pu(c1)+(1-p)u(c2),where for any x<7,000,u(x)=2x,and for x greater than or equal to 7,000 u(X)=14,000+x. a.Sally will be risk averse if her income is less than$7,000 but risk loving if her income is more than $7,000. b.Sally will be risk neutral if her income is less than $7,000 and risk averse if her income is more than $7,000. c.Sally will never take a bet if there is a chance that it leaves her with wealth less than $14,000. d.For bets that involve no chance of her wealth exceeding $7,000 ,Sally will take any bet that has a positive expected net payoff. e.None of the above. 问答题(80%) 1.(10%) Charlie's utility function is XAXB.The price of apples used to be $1,the price of bananas used to be $2,and his income used to be $40.Now the price of apples increases to $5 and the price of bananas stayed constant, a.How many apples did Charlie consume before the price change? b.Please calculate the substitution effect. 2.(10%) Ethel is trying to decide whether to have 0 car,1 car,2cars.If x is the number of cars she has and y is the amount of money she has per year to spend on other stuff,Ethel's utility function is U(x,y),where U(0,y)=y^1/2 U(1,y)=(15/14)y^1/2,and U(2,y)=(10/9)y^1/2.Suppose that it costs$2,000 a year to have 1 car and$4,000 a year to have 2 cars.Ethel finds that the right thing to do depends on her income. a.What is her willingness to pay for 1 car if her income is M? b.What is the lowest income at which she would have a car? 3.(10%) The inverse demand function for grapefruit is defined by the equation p=145-6q,where q is the number of units sold.The inverse supply function is defined by p=5+4q.A tax of $20 is imposed on suppliers for each unit of grapefruit that they sell. a.Before the tax implement,what is the price of grapefruit in the equilibrium? b.Please calculate the consumer surplus before and after the tax. c.What is the deadweight loss(excess burden)in this case? 4.(15%) In an isolated peasant village,the only crop is corn.Good harvests alternate with bad harvests.This year the harvest will be 1,000 bushels.Next year it will be 150 bushels.There is no trade with the outside world.Corn can be stored,but rats will eat 25%of what is stored in a year.The villagers have the Cobb-Douglas utility function U(c1,c2)=c1c2,where c1 is consumption this year and c2 is consumption next year. a.Draw a budget line for the village with this year's consumption on the horizontal axis and next year's consumption on the vertical axis.on your graph show the quantities at which the budget line intercepts the vertical and horizontal axes. b.How much will the villagers consume this year? c.How much will the rats eat? d.How much will the villagers consumer next year? 5.(15%) Ernie's wage rate is$10 an hour.He has no earnings other than his labor income. His utility function is U(C,L)=CR^2,where C is the amount of money he spends on consumption,and R is the number of hours a day he spends not working. a.Write an equation that describes Ernie's budget constraint. b.How many hours does Ernie choose to work per day? c.How much money does he spend on consumption per day? 6.(10%) The certainty equivalent of a gamble is defined to be the amount of money which, if you were promised it with certainty,would be indifferent to the gamble. a.If an expected utility maximizer has a von Neuman-Morgenstern utility funtion U(W)=W^1/2 (where W is wealth)and if the probability of events 1 and 2 are both 1/2,write a formula for the certainty equivalent of a gamble that gives you x if event 1 happens and y if event 2 happens. b.Generalize your formula in part (a)to the case where probability of event 1 is p and the probability of event 2 is 1-p. --

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