经济学基础第一次作业09答案

西方经济学第一次作业

1. 假设大学里篮球票的价格是由市场力量决定的。现在，需求与供给表如下：价格(美元) 需求量(张) 供给量(张)

4 10000 80009

8 8000 8000

12 6000 8000

16 4000 8000

20 2000 8000

a．画出需求曲线和供给曲线。这条供给曲线有什么不寻常之处？为什么会是这样的？

b．篮球票的均衡价格和均衡数量是多少？

c．明年你们大学计划共增加5000名学生。增加的学生的需求表如下：

价格(美元) 需求量(张)

4 4000

8 3000

12 2000

16 1000

20 0

现在把原来的需求表与新生的需求表加在一起计算整个大学的新需求表。新的均衡价格和均衡数量是多少？

a. As Figure 2-25 shows, the supply curve is vertical. The constant supply makes sense

because the basketball arena has a fixed number of seats no matter what the

price.

Figure 2-25

b. Quantity supplied equals quantity demanded at a price of $8. The equilibrium

quantity is 8,000 tickets.

c.

The new equilibrium price will be $12, which equates quantity demanded to

quantity supplied. The equilibrium quantity is 8,000 tickets.

2. 假设公务乘客和度假乘客对从纽约到波士顿之间民航机票的需求如下：

价格需求量需求量

(美元) (公务乘客) (度假乘客)

150 **** ****

200 2000 800

250 1900 600

300 1800 400

a．当票价从200美元上升到250美元时，公务乘客的需求价格弹性为多少？度假乘客的需求价格弹性为多少？(用中点法计算。)

b．为什么度假乘客与公务乘客的需求价格弹性不同？

a. For business travelers, the price elasticity of demand when the price of tickets rises from

$200 to $250 is [(2,000 - 1,900)/1,950]/[(250 - 200)/225] = 3/13 = 0.23. For

vacationers, the price elasticity of demand when the price of tickets rises from

$200 to $250 is [(800 - 600)/700] / [(250 - 200)/225] = 9/7 = 1.29.

b. The price elasticity of demand for vacationers is higher than the elasticity for

business travelers because vacationers can more easily choose a different mode

of transportation (like driving or taking the train). Business travelers are less

likely to do so since time is more important to them and their schedules are less

adaptable.

3. 这是一个热天，Bert口干舌燥。下面是他对一瓶水的评价：

对第一瓶水的评价 7美元

对第二瓶水的评价 5美元

对第三瓶水的评价 3美元

对第四瓶水的评价 1美元

a．根据以上信息推导出Bert的需求表。画出他对瓶装水的需求曲线。

b．如果一瓶水的价格是4美元，Bert会买多少瓶水？Bert从他的购买中得到了多少消费者剩余？在你的图形中标出Bert的消费者剩余。

c．如果价格下降到2美元，需求量会有何变化？Bert的消费者剩余会有何变化？用你的图形说明这些变化。

a. Bert’s demand schedule i s:

Price Quantity Demanded

More than $7 0

$5 to $7 1

$3 to $5 2

$1 to $3 3

$1 or less 4

Bert’s demand curve is shown in Figure 9.

Figure 9

b. When the price of a bottle of water is $4, Bert buys two bottles of water. His

consumer surplus is shown as area A in the figure. He values his first bottle of

water at $7, but pays only $4 for it, so has consumer surplus of $3. He values

his second bottle of water at $5, but pays only $4 for it, so has consumer surplus

of $1. Thus Bert’s t otal consumer surplus is $3 + $1 = $4, which is the area of

A in the figure.

c. When the price of a bottle of water falls from $4 to $2, Bert buys three bottles of

water, an increase of one. His consumer surplus consists of both areas A and B