国际经济学(克鲁格曼)教材答案

Chapter 3

1. Home has 1200 units of labor available. It can produce two goods, apples and bananas.

The un it labor requireme nt in apple product ion is 3, while in banana producti on it is 2.

a. Graph out the product ion possibilities fron tier:

apple

b. What is the opport unity cost of apples in terms of banan as?

c. In the absenee of trade, what would the price of apples in terms of bananas be?

In the abse nee of trade, since labor is the only factor of product ion and supply decisi ons are determined by the attempts of individuals to maximize their earnings in a competitive

economy, only whe n P a/P b a La /a Lb will both goods be produced. So P a/P b 1.5

2. Home is as described in problem 1. There is now also another country, Foreign, with a labor

force of 800. Foreig n ' un it labor requireme nt in apple product ion is 5, while in banana

product ion it is 1.

a. Graph Foreign ' production possibilities frontier:

b. Con struct the world relative supply curve.

a La

a Lb

1.5

Q* banana

3. Now suppose world relative dema nd takes the followi ng form: Dema nd for apples/dema nd

for bananas = price of banan as/price of apples.

a . Graph the relative dema nd curve along with the relative supply

curve:

D a ■/ When the market achieves its equilibrium, we have

D b IT kN

b . What is the equilibrium relative price of apples?

The equilibrium relative price of apples is determined by the intersection of the RD and RS

curves.

1 RD: x y

x [0,0.5) y 1.5

RS: x 0.5 y [1.5,5]

x (0.5,] y 5

••• x 0.5

Q a Q a

Q b Q b

1 /• RD is a hyperbola y x

Pl/Pb a / d —乍

D a /D b 诃

rhe World Relative Supply Cuive

••• P e a/P e b 2

c. Describe the pattern of trade.

•/ P a /P b P e a /P e b P a/ P b

• I n this two-co untry world, Home will specialize in the apple product ion, export apples

and import banan as. Foreig n will specialize in the banana product ion, export bananas

and import apples.

d . Show that both Hom

e and Foreign gain from trade.

RD: x 1 y

x [0,1) y 1.5

RS: x 1 y [1.5,5

]

x (1,] y 5

• x 2

y

1.5

3

• P e a/P e b 1.5

Intern ati onal trade allows Home and Foreig n to con sume any where with in the colored lin es, which lie outside the coun tries' product ion possibility fron tiers. And the in direct

method, specializ ing in produci ng only one producti on the n trade with other coun try, is a more efficient method than direct production. In the absence of trade, Home could gain three bananas by foregoing two apples, and Foreign could gain by one foregoing five banan as.

Trade allows each country to trade two bananas for one apple. Home could the n gain four

bananas by foregoing two apples while Foreign could gain one apple by forego ing only two banan as. So both Home and Foreig n gain from trade.

4. Suppose that in stead of 1200 workers, Home had 2400. Find the equilibrium relative price. What can you say about the efficie ncy of world product ion and the divisio n of the gains from trade betwee n Home and Foreig n in this case?

~n.

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EC

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400

Foreign^ PPF

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