中级微观经济学期中考试试卷及答案

中山大学国际商学院学生会

2006-2007第二学期“微观经济学II”期中考试试卷

警 示 《中山大学授予学士学位工作细则》第六条：“考试作弊不授予学士学位。”

姓名 学号 专业 成绩

1. Given TM = f (Q) in the following Fig. 1, draw corresponding AM and MM in Fig.

2. (10 points)

TM

Fig. 1 Q

AM, MM

Fig. 2 Q

①画错AM起点的扣一半（5分）（AM起点在无穷远处） ②拐点（1分）

③MM在AM最低点之前位于AM下方（1分） ④MM穿过AM的最低点（1分）

⑤MM在穿过AM最低点后位于AM的上方(1分)

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⑥MM的起点位于纵轴上（1分）

2. The price of bread is strictly controlled. Loaves of bread cost $1 each at the government store. However, a consumer can purchase only 5 loaves at the government store, and any additional loaves cost $5 on the black market. The consumer has an income of $30 and purchases bread and one other good, X. The price of X is $1.

a. Draw the consumer's budget constraint. (5 points) b. Suppose the market for bread is decontrolled, and the price is $2 a loaf. Draw the new budget constraint on the same diagram. (5 points) c. On the diagram, show a consumer who prefers the new policy. (5 points)

d. On a new graph with both the old and the new budget constraints, show a consumer who is indifferent between the two policies. (5 points)

a、两段budget line,每段2、5分（纵轴为Money,横轴为Bread,无标明的扣2分）

b、新budget line斜率为-2（3分）纵轴坐标为30（1分），横轴为15（1分）

c、要画出至少两条indifferent curve,与斜率为-2的budget line相切的indifferent curve位于与原来的budget line相切的无差异曲线的上方（5分）

d、无差异曲线要与新旧两条budget line相切（凡画成打折的无差异曲线扣1分）

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3. Each year Sam grows 200 units of wheat and 100 units of sunflower seeds for his own consumption and for sale.

a. If the price of wheat is $2 per unit and sunflower seeds sell for $10 per unit, Sam chooses to sell 20 units of the sunflower seeds. Graph to show Sam’s utility-maximizing situation and indicate also his initial production levels. (10 points) b. Suppose somehow sunflower seeds price falls to also $2. Will Sam be made better-off or worse-off by this price decline? Or is the situation ambiguous? Show that

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if Sam is to be made better-off, he must become a seller of wheat and a buyer of sunflower seeds. (10 points)

a、标出endowment point:wheat200,sunflower seeds100(2

分);budget line slope:-1/5(wheat在横轴，sunflower seeds在纵轴)（4分）；标出utility maximization point(300,80)（3分） 在(300,80)处画出与budget line相切的无差异曲线（1分）无差异曲线画得不好的扣1分

b、（wheat在横轴，sunflower seeds在纵轴）指出或在图上标出价格变化后，预算线绕禀赋点顺时针旋转一个角度，新预算线斜率为-1（4分），无标明斜率为-1的扣3分；画出经过原来的最优消费决策点并且与新预算线相交的无差异曲线（相交即新预算线上有一段位于经过原来的最优消费决策点的无差异曲线的上方）（3分）；画出与新预算线相切的无差异曲线（1分），且位于经过原来最优消费决策点的无差异曲线的上方）（2分）；新的最优消费决策点要位于禀赋点的左上方

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中山大学国际商学院学生会

4. Assume individuals are choosing between housing services (H) measured in square feet and consumption of all other goods (C) in dollars. Suppose now the government agrees to subsidize consumers by paying 50% of their housing cost. a. Draw to show how will the budget line of a typical consumer change? Show also her original choice and the new choice. (5 points)

b. Show in the same diagram the minimum amount of income supplement the government would have to give the consumer instead of the housing subsidy to make them as well off as she was in Part a. (10 points)

a、首先在图上指出budget line的绝对值会变为原来的1/2（3分）；标出original choice (1分)new choice (1分)

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