Microsoft Word - HW02_ans.doc

Size: px

Start display at page:

Download "Microsoft Word - HW02_ans.doc"

蠡域习
5 years ago
Views:

1 組別姓名與學號 Homework #2 Microeconomics (I), Fall 2010 Due day: 28th Oct., 2010 Part I. Multiple Choice: 60% (5% each) Please fill your answers in below blanks, each question only have one answer C B C A C B B D D D A B 1.Indifference curves are downward sloping because of the assumption of A) completeness. B) transitivity. C) more is better. D) All of the above. 2.Convexity of indifference curves implies that consumers are willing to A) give up more y to get an extra x the more x they have. B) give up more y to get an extra x the less x they have. C) settle for less of both x and y. D) acquire more x only if they do not have to give up any y. 3.If the utility function (U) between food (F) and clothing (C) can be represented as U = FxC, the marginal utility of food equals A) F/C B) C/F C) 1/2 C/F D) 1/2 F/C 4.If two goods, x and y, are perfect substitutes, then which of the following best represents the utility function for the two goods? A) U = x + y B) U = x y C) U = x 2 + y 2 D) Any of the above. 1

2 5.Sarah has the utility function U(X,Y)=X 0.5 Y When Sarah consumes X=2 and Y=6 she has a marginal rate of substitution of A) -12 B) -1/6 C) -6 D) -1/12 6.If both prices increases by 50% A) budget constraint will be unchanged. B) slope of the budget constraint stay the same. C) slope of the budget constraint will decrease. D) budget constraint will shift outward in a parallel fashion. 7.Max has allocated $100 toward meats for his barbecue. His budget line and an indifference map are shown in the above figure. What happens if Max s mother gives him 10 pounds of burger? A) Max would have preferred receiving the dollar-value of the burger. B) Max is indifferent between this gift and the dollar-value of the burger. C) Max prefers this gift to the dollar-value of the burger. D) None of the above. >> 第七題詳解..此題解題的方向是, 假設 Max 收到 10 磅的漢堡, 跟與 10 磅漢堡等值的錢時, 預算線會發生怎樣的變化假設 Max 收到 10 磅的漢堡, 那麼他的預算線就會變成兩段式 ( 因為他就算不買漢堡還是會有媽媽的 10 磅, 所以有一段是水平線 ) Y=20; 4(X-10)+5Y=100; 假設 X 是漢堡,Y 是雞肉 if 0<X<10 if X 10 2

3 而假如 Max 收到的是與 10 磅漢堡等值的錢時, 就等同於他擁有的金錢增多 40 元 ( 依圖可算得一磅漢堡為 4 元 ), 所以他的預算線變成 4X+5Y=140 將 4(X-10)+5Y=100 移項一下, 就會發現兩條限制式是一樣的然後依圖所示的無異曲線式樣, 無異曲線在多 10 磅漢堡或 40 元時的最適解是一樣的, 故此答案是兩者沒有差別 8.A competitive equilibrium is described by A) a price only. B) a quantity only. C) the excess supply minus the excess demand. D) a price and a quantity. 9.The above figure shows a graph of a market for pizzas in a large town. At a price of $10, the market A) is not in equilibrium. B) has excess supply. C) does not have excess demand. D) All of the above. 10.If the demand curve for a good is horizontal and the price is positive, then a leftward shift of the supply curve results in A) a price of zero. B) an increase in price. C) a decrease in price. D) no change in price. 11.The market demand for wheat is Q = 100-2p + 1 p b + 2Y. If the price of wheat, p, is $2, and 3

4 the price of barley, p b, is $3, and income, Y, is $1000, the income elasticity of wheat is A) 2 (1000/2099). B) 2. C) 1/2 (1000/2099). D) cannot be calculated from the information provided. 12.The demand equation Q=0.5p is equivalent to the log-linear demand equations A) Q=ln(0.5)-0.75ln(p) B) ln(q)=ln(0.5)-0.75ln(p) C) ln(q)= ln(p) D) ln(q)=ln(0.75)-0.5ln(p) Part II. Problems: 40% 1. If demand for show tickets is described by the equation Q D =100-p, and supply is Q S =20+p, find the equilibrium price and quantity. How would your answer change if the supply curve shifted to Q S =10+p due to increases in actor salaries?(10%) Set QD = QS and solve. For QS = 20 + p 100- p = 20 + p p* = 40 Q* = 60 For Q = 10 + p 100-p = 10 + p p* = 45 Q* = For each of the utility functions below, draw a set of indifference curves showing utility levels U=12, U=16, and U=24.(20%) a. U =XY b. U =X+Y c. U =X -Y d. What is true about the commodities in (b)? e. What about the commodities in (c)? a. 4

5 b.. c d. They are perfect substitutes. e. X is a good, and Y is a bad, providing exactly the opposite of X in utility per unit. 關於 e 的部份, 很多同學寫 Y 是 inferior good( 劣等財 ), 這並不正確 Inferior 是定義在所得上 ( 所得上升但需求會下降 ), 跟無異曲線的形態沒很大的關係對於 C 中的無異曲線形態大家可能會有點摸不著頭腦, 但如果參考它的 utility function: U=X-Y, 假如你以 X=0, Y=1 代入, 會發現 U = -1 <0, 即是 Y 是負效用, 所以 Y 是 Bad Inferior good 跟 bad 是完全不同的東西, 前者仍會帶來正效用, 但後者卻不會 3. Confirm that if a consumer s utility function is described by U=2X+Z, and prices are p X =2 and p Z =1, there is no unique utility maximizing solution regardless of income level. What does this tell you about X and Z as commodities? (Hint: draw a graph showing a budget constraint and indifference curve using the information provided.)(10%) 5

6 Because the commodities are perfect substitutes, and the price ratio is equal to the MRS, any budget line drawn would be coincident with some indifference curve, resulting in no unique solution. The consumer is equally happy choosing any point on the budget line. 6

1

目录第一部分开篇导读及本书点评小时高清视频讲解... 7 一开篇导读... 7 二本书点评及总结 ( 结束语 )... 第二部分辅导讲义 34 小时高清视频讲解... 3 第章市场... 3 第章预算约束... 5 第 3 章偏好... 第 4 章效用... 7 第 5 章选