短期与长期（short run vs．long mn)

短期(short run)

因此，这种管制的改变会使持有货币更有吸引力。

a．这种变动如何影响货币需求？

b．货币流通速度会发生什么变动？

c．如果美联储使货币供给保持不变。短期和长期产出与物价将发生什么变动？

d．对这种管制变动，美联储的反应应该是保持货币供给不变吗？为什么是或为什么不是？

Suppose that a change in government regulations allows banks to start paying interest on checking accounts. Recall that the money stock is the sum of currency and demand deposits, including checking accounts, so this regulatory change makes holding money more attractive.

a．How does this change affect the demand for money？

b．What happens to the velocity of money？

c．If the Fed keeps the money supply constant, what will happen to output and prices in the short run and in the long run？

d．Should the Fed keep the money supply constant in response to this regulatory change？ Why or why not？

使用与练习1相同的信息。（1)推导厂商的短期供给曲线。（提示:画出成本曲线的基本形状。)（2)假如市

使用与练习1相同的信息。

(1)推导厂商的短期供给曲线。(提示:画出成本曲线的基本形状。)

(2)假如市场中有100家相同的厂商，市场供给曲线是怎样的？

Use the same information as in Exercise 1.

a. Derive the firm's short - run supply curve. (Hint: You may want to plot the appropriate cost curves. )

b. If 100 identical firms are in the market, what is the industry supply curve？

解释为何实际汇率的随后变化满足实际利率平价的条件。

In the short run of a model with sticky prices，a reduction in the money supply raises the nominal interest rate and appreciates the currency．What happens to the expected real interest rate？ Explain why the subsequent path of the real exchange rate satisfies the real interest parity condition．

假设某一特殊行业的信息如下:Q^D=6500-100P市场需求Q^S=1200P市场供给C（q)=722+q卐

假设某一特殊行业的信息如下:

Q^D=6500-100P市场需求

Q^S=1200P市场供给

C(q)=722+q²/200厂商总成本

MC(q)=2q/200

厂商边际成本

假定所有厂商完全同质，而且市场是完全竞争的。

(1)计算均衡价格、均衡产量、厂商供给产量和每家厂商的利润。

(2)在长期将有厂商进入还是退出市场？试解释。进入或退出将会对市场产生何种影响？

(3)在长期，每家企业销售其产品的最低价格为多少？利润是正的、负的还是为零？解释你的结论。

(4)在短期，每家企业销售其产品的最低价格为多少？利润是正的、负的还是为零？解释你的结论。

Suppose you are give the following information about a particular industry:

Q^D=6500-100P Market demand

Q^S=1200P Market supply

C(q)=722+q²/200 Firm total cost function

MC(q)=2q/200 Firm marginal cost function

Assume that all firms are identical and that the market is characterized by pure competition.

a. Find the equilibrium price, the equilibrium quantity, the output supplied by the firm, and the profit of each firm.

b. Would you expect to see entry into or exit from the industry in the long run？ Explain. What effect will entry or exit have on market equilibrium？

e. What is the lowest price at which each firm would sell its output in the long run？ Is profit positive, negative, or zero at this price？ Explain.

d. What is the lowest price at which each firm would sell its output in the short run？ Is profit positive, negative, or zero at this price？ Explain.

(1)企业目前的产量为100单位，成本最小化的劳动和资本分别为20和5。在图上用等产量线和等成本线表示出来。

(2)企业想将产量扩大为140单位，如果资本在短期固定，需要多少劳动？在图形上表示出来，并计算企业新的成本。

(3)在图形上表示出企业在长期生产140单位产品的成本最小化劳动和资本投入。

(4)如果边际技术替代率为K/L,计算生产140单位产品的最优劳动和资本投入。

Suppose that a firm' s production is q= 10L1/2K1/2. The cost of a unit of labor is $ 20 and the cost of a unit of capital is $ 80. a The firm is currently production 100 unis of output and has determined that the cost - mini-mizing quantities of labor and capital are 20 and 5, respectively. Graphically illustrate this using isoquants and isocost lines.

b，The firm now wants to increase output to 140 units. If capital is fixed in the short run, how much labor will the firm require？ Illustrator this graphically and find the firms new total cost.

c. Graphically identify the cost - minimizing level of capital and labor in the long run if the firm wants to produce 140 units.

d. If the marginal rate of technical substitution is K/L, find the optimal level of capital and labor required to produce the 140 units of output.

Is expansionary fiscal policy more likely to increase output in an economy with widespread long-term contracts or in one in which contracts are fixed for very short periods of time？

些进口价格而使P下降。如果永久性财政扩张的确使P有轻微下降，那么它对产出无影响这一结论是否仍成立(同上，假定初始条件为长期均衡)？

Our model takes the price level P as given in the short run，but in reality the currency appreciation caused by a permanent fiscal expansion might cause P to fall a bit by lowering some import prices．If P can fall slightly as a result of a permanent fiscal expansion，is it still true that there are no output effects？ (As above，assume an initial long-run equilibrium．)

When consumers face rising gasoline prices, they typically

A.increase their quantity demanded in the short run but reduce their quantity demanded in the long run.

B.reduce their quantity demanded more in the short run than in the long run.

C.reduce their quantity demanded more in the long run than in the short run.

D.do not reduce their quantity demanded in the short run or the long run.