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第32章《总供给与总需求》

(2008-10-10 20:59:01)
标签:

杂谈

分类: 《经济学原理》习题选答

复习题:

1. Name two macroeconomic variables that decline when the economy goes into a recession. Name one macroeconomic variable that rises during a recession.写出当经济衰退时,下降的两个宏观经济参数,上升的一个宏观经济参数。

答:实际GDP下降,投资下降。失业率上升。


2. Draw a diagram with aggregate demand, short-run aggregate supply, and long-run aggregate supply. Be careful to label the axes correctly.

答:

第32章《总供给与总需求》
3. List and explain the three reasons why the aggregatedemand curve is downward sloping.

答:首先,价格水平降低,由于财富效应,导致人们消费更多,使总需求上升。其次,利率效应,较低的价格水平,使利率降低,促进了投资,投资带动需求。第三,汇率效应,美国利率水平低,有些美国资本需求海外投资,增加了外汇市场的美元供给,美元汇率下降贬值,相对于国外产品,美国产品更便宜了,所以出口需求增加。


4. Explain why the long-run aggregate-supply curve is vertical.

答:因为长期来看,一个经济的产品和服务总供给,取决于资本、资源和劳动的总供给以及将这些资源转换为产品和服务的技术。价格水平不影响长期实际GDP的决定因素。


5. List and explain the three theories for why the short-run aggregate-supply curve is upward sloping.

答:短期供应曲线向上倾斜,首先因为粘性工资理论,当整体物价下降后,工资并不能很快下降,由于工资是成本中很重要的部分,所以导致生产成本不能及时下降,雇主只要减少员工,导致产出下降。其次是,粘性价格理论,比如货币供给紧缩,这将降低长期的物价总水平,但是由于菜单成本,有些企业没有及时降价,导致销售不畅,进一步导致产量降低。第三是,错觉理论,当生产者看到自己的产品价格价格下降后,并没有注意到其它产品也在降价,只是认为自己产品的相对价格下降了,所以减少产量。


6. What might shift the aggregate-demand curve to the left? Use the model of aggregate demand and aggregate supply to trace through the effects of such a shift.什么会引起总需求曲线左移?用总供应和总需求模型探讨这种移动的影响。

答:其它一些非价格因素的变化,比如消费支出减少(增加储蓄),投资减少,政府开支减少(比如削减军费开支),出口减少(比如国外经济衰退,导致出口减少)

第32章《总供给与总需求》

上图讨论了总需求的这种变化的影响。经济开始处于均衡状态,均衡点是A,当总需求左移后,经济从A点移动到B点,价格和产量都发生下降。随着时间推移,人们调整自己的感觉、工资和价格,增加供应,经济从B点来到C点,结果是产量不变,价格总水平降低了。


7. What might shift the aggregate-supply curve to the left? Use the model of aggregate demand and aggregate supply to trace through the effects of such a shift.什么会引起总供给曲线左移?用总供应和总需求模型探讨这种移动的影响。

答:资本存量下降,劳动力供应下降,自认失业率上升,都会导致长期曲线和短期总供应曲线左移。价格变化,只会导致短期总供应曲线左移。

第32章《总供给与总需求》

经济从A点到B点,然后会返回A点。

 

应用题:

1. Why do you think that investment is more variable over the business cycle than consumer spending? Which category of consumer spending do you think would be
most volatile: durable goods (such as furniture and car purchases), nondurable goods (such as food and clothing), or services (such as haircuts and medical
care)? Why? 为何经济周期中投资变动比消费变动大?你认为消费支出中,哪一类变动最剧烈?耐用品(家具汽车)?非耐用品(食物和衣服)?服务(理发和医疗)?

答:相比家庭缩减消费,公司缩减投资更容易。在经济衰退期,公司知道他们的产品卖不了太多,所以不想扩大生产,推迟购买资本(不再建新工厂,不再买新机器)。大部分消费支出都是必需品,例如食物,在经济衰退时,也不可能减少太多,因此,随着经济周期波动,投资变化更明显。同样道理,耐用消费品的消费受经济周期影响大。


2. 假设经济处于长期均衡。

a, 用图形说明经济的状态,标出总需求,长期总供给和短期总供给。

答:

第32章《总供给与总需求》

如上图,总供给1,总需求1。
b. 假设股市崩溃导致总需求减少,用图说明短期物价总水平和产量变化。失业率有何变化?

答:股市崩溃导致财富缩水,总需求下降,总需求曲线左移,导致产量和价格下降(B点)。因为产量低于自然产量,所以失业率将高于自然失业率。
c. 用总供给的粘性工资理论,解释长期中,物价和产量将发生什么变动(假设政策不变),在这种调整中,预期的物价水平起什么作用?用图说明。

答:如果物价水平降低后,名义工资没有变化,公司将裁员和减产。随着时间流逝,人们预期改变价格将走低,这种价格的影响,使人们消费量增加,产量增加。于是短期总供给曲线向右移动。经济回到自然产量。

 


3. Explain whether each of the following events will increase, decrease, or have no effect on long-run aggregate supply. 解释下列事件,将使长期总供给增加、减少还是没有影响?
a. The United States experiences a wave of immigration.

答:劳动力增加了,长期供应曲线右移。
b. Congress raises the minimum wage to $10 per hour.

答:当议会通过最低工资法后,自然失业率要增加,所以长期总供应曲线左移。
c. Intel invents a new and more powerful computer chip.

答:新芯片使劳动生产率提高,同样的投入得到更多产出,所以右移。

d. A severe hurricane damages factories along the east coast.

答:资本存量减少了,所以长期总供给曲线左移。


4. In Figure 31-8, how does the unemployment rate at points B and C compare to the unemployment rate at point A? Under the sticky-wage explanation of the
short-run aggregate-supply curve, how does the real wage at points B and C compare to the real wage at point A? 与A点失业率相比,B点,C点是多少?根据粘性工资对短期总供给的解释,与A点的实际工资相比,B点,C点的实际工资是多少?

第32章《总供给与总需求》

答:B点的失业率比A点高,因为B点的产量比A点低。C点的失业率和A点一样。A点和B点的名义工资是一样的。C点在长期总供给曲线上,所以实际工资和A点应该一样。因为C点物价总水平比A点低,所以C点的名义工资也应该比A点低。

 


5. Explain why the following statements are false.
a. “The aggregate-demand curve slopes downward because it is the horizontal sum of the demand curves for individual goods.” 总需求曲线向右下方倾斜,是因为它是个别物品需求曲线的相加。

答:不对。正确解释是,物价下降后,由于财富效应,利率效应和汇率效应,导致人们总需求增加。


b. “The long-run aggregate-supply curve is vertical because economic forces do not affect long-run aggregate supply.”

答:错。经济力量影响长期总供给,比如劳动力增加。之所以是垂直,是因为物价水平不影响总供给。


c. “If firms adjusted their prices every day, then the short-run aggregate-supply curve would be horizontal.”如果企业每天调整产品价格,那么短期总供给曲线就是水平的。

答:错。如果企业每天调整自己产品价格,短期供给曲线就是垂直的。如果企业保持自己的产品价格不变,则短期供给曲线才是水平的。


d. “Whenever the economy enters a recession, its long-run aggregate-supply curve shifts to the left.” 当经济进入衰退,长期供给曲线向左移动。

答:错。当短期总供给曲线或需求总曲线左移时,经济进入衰退。

 


6. For each of the three theories for the upward slope of the short-run aggregate-supply curve, carefully explain the following:
a. how the economy recovers from a recession and returns to its long-run equilibrium without any policy intervention没有政策干预,经济也能自己复苏。

答:根据工资粘性理论,价格粘性理论和错觉理论,经济能自己复苏。
b. what determines the speed of that recovery 什么决定复苏速度。

答:复苏的速度取决于工资、价格和预期调整速度。


7. Suppose the Fed expands the money supply, but because the public expects this Fed action, it simultaneously raises its expectation of the price level. What will happen to output and the price level in the short run? Compare this result to the outcome if the Fed expanded the money supply but the public didn’t
change its expectation of the price level.假设Fed扩大货币供给,但由于公众预期到了Fed这个行动,所以这次行动提高了物价水平预期,短期中产量和物价水平将发生什么变动?把这种结果与Fed扩大货币供给,但公众没有改变物价水平预期时的结果相比。

答:

第32章《总供给与总需求》

当美联储增加货币供应,这次行动,提高了物价水平预期,导致总需求曲线右移,短期总供给曲线左移(,经济从A点移动到B点,产量和物价水平都不发生变化。如果人们没有改变物价预期,短期总供给曲线不左移,则经济到C点。


8. Suppose that the economy is currently in a recession. If policymakers take no action, how will the economy evolve over time? Explain in words and using an
aggregate-demand/aggregate-supply diagram.

答:

第32章《总供给与总需求》

如图,衰退中的经济在A点,如果政府不采取措施,会自动回到B点。


9. Suppose workers and firms suddenly believe that inflation will be quite high over the coming year. Suppose also that the economy begins in long-run
equilibrium, and the aggregate-demand curve does not shift.假设企业和工人突然认为,下一年通货膨胀将非常高,再假设经济开始时,处于长期均衡,而且总需求曲线并没有移动。
a. What happens to nominal wages? What happens to real wages?名义工资会发生什么变动? 实际工资呢?

答:如果认为来年通胀很高,工人将要求增加工资,如果物价总水平上涨不及工资上涨,实际工资将增加,公司将减少雇员。
b. Using an aggregate-demand/aggregate-supply diagram, show the effect of the change in expectations on both the short-run and long-run levels of prices and output.

答:

第32章《总供给与总需求》

短期影响A-〉B,长期影响,B又回到A。
c. Were the expectations of high inflation accurate? Explain.

答:短期看,通胀预期是正确的,价格上升了。但是长期看,通胀预期是错误的。


10. Explain whether each of the following events shifts the short-run aggregate-supply curve, the aggregatedemand curve, both, or neither. For each event that does shift a curve, use a diagram to illustrate the effect on the economy.下列事件影响短期总供给曲线还是总需求,还是两者都?
a. Households decide to save a larger share of their income.

答:总需求左移,价格下降,产量下降。
b. Florida orange groves suffer a prolonged period of below-freezing temperatures.

答:短期总供给左移。导致价格上升,产量下降。
c. Increased job opportunities overseas cause many people to leave the country.

答:导致短期总供给曲线和总需求都左移。价格是升还是降,取决于哪个因素占主导。

 


11. For each of the following events, explain the short-run and long-run effects on output and the price level, assuming policymakers take no action. 如果政府不干预,下列事件对价格和产量的长期和短期影响。
a. The stock market declines sharply, reducing consumers’ wealth.

答:

第32章《总供给与总需求》
b. The federal government increases spending on national defense.

答:

第32章《总供给与总需求》
c. A technological improvement raises productivity.

答:

第32章《总供给与总需求》


d. A recession overseas causes foreigners to buy fewer U.S. goods.

答:

第32章《总供给与总需求》


12. Suppose that firms become very optimistic about future business conditions and invest heavily in new capital equipment.
a. Use an aggregate-demand/aggregate-supply diagram to show the short-run effect of this optimism on the economy. Label the new levels of prices and real output. Explain in words why the aggregate quantity of output supplied changes.说明这种乐观对经济的短期影响,标出新的物价水平和实际产量。

答:

第32章《总供给与总需求》


If firms become optimistic about future business conditions and invest a lot, the result is shown in Figure 17.  The economy begins at point A with aggregate-demand curve AD1 and short-run aggregate-supply curve AS1.  The equilibrium has price level P1 and output level Y1.  Increased optimism leads to greater investment, so the aggregate-demand curve shifts to AD2.  Now the economy is at point B, with price level P2 and output level Y2.  The aggregate quantity of output supplied rises because the price level has risen and people have misperceptions about the price level, wages are sticky, or prices are sticky, all of which cause output supplied to increase.


b. Now use the diagram from part (a) to show the new long-run equilibrium of the economy. (For now, assume there is no change in the long-run aggregate-supply curve.) Explain in words why the aggregate quantity of output demanded changes
between the short run and the long run.

答:Over time, as the misperceptions of the price level disappear, wages adjust, or prices adjust, the short-run aggregate-supply curve shifts up to AS2 and the economy gets to equilibrium at point C, with price level P3 and output level Y1.  The quantity of output demanded declines as the price level rises.


c. How might the investment boom affect the longrun aggregate-supply curve? Explain.

答:The investment boom might increase the long-run aggregate-supply curve because higher investment today means a larger capital stock in the future, thus higher productivity and output

 


13. In 1939, with the U.S. economy not fully recovered from the Great Depression, President Roosevelt proclaimed that Thanksgiving Day would fall a week earlier than usual so that the shopping period before Christmas would be lengthened. Explain this decision, using the model of aggregate demand and aggregate supply.感恩节提前一周,以便圣诞节前的销售延长

答:

 第32章《总供给与总需求》

The idea of lengthening the shopping period between Thanksgiving and Christmas was to increase aggregate demand.  As Figure 18 shows, this could increase output back to its long-run equilibrium level.

 

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