曼昆 宏观经济经济学第九版 英文原版答案3.docx

1、曼昆 宏观经济经济学第九版 英文原版答案3Answers to Textbook Questions and ProblemsCHAPTER 3National Income: Where It Comes From and Where It GoesQuestions for Review1. The factors of production and the production technology determine the amount of output an economy can produce. The factors of production are the inputs

2、 used to produce goods and services: the most important factors are capital and labor. The production technology determines how much output can be produced from any given amounts of these inputs. An increase in one of the factors of production or an improvement in technology leads to an increase in

3、the economys output.2. When a firm decides how much of a factor of production to hire or demand, it considers how this decision affects profits. For example, hiring an extra unit of labor increases output and therefore increases revenue; the firm compares this additional revenue to the additional co

4、st from the higher wage bill. The additional revenue the firm receives depends on the marginal product of labor (MPL) and the price of the good produced (P). An additional unit of labor produces MPL units of additional output, which sells for P dollars per unit. Therefore, the additional revenue to

5、the firm is P MPL. The cost of hiring the additional unit of labor is the wage W. Thus, this hiring decision has the following effect on profits: Profit = Revenue Cost = (P MPL) W. If the additional revenue, P MPL, exceeds the cost (W) of hiring the additional unit of labor, then profit increases. T

6、he firm will hire labor until it is no longer profitable to do sothat is, until the MPL falls to the point where the change in profit is zero. In the equation above, the firm hires labor until Profit = 0, which is when (P MPL) = W. This condition can be rewritten as: MPL = W/P. Therefore, a competit

7、ive profit-maximizing firm hires labor until the marginal product of labor equals the real wage. The same logic applies to the firms decision regarding how much capital to hire: the firm will hire capital until the marginal product of capital equals the real rental price.3. A production function has

8、 constant returns to scale if an equal percentage increase in all factors of production causes an increase in output of the same percentage. For example, if a firm increases its use of capital and labor by 50 percent, and output increases by 50 percent, then the production function has constant retu

9、rns to scale. If the production function has constant returns to scale, then total income (or equivalently, total output) in an economy of competitive profit-maximizing firms is divided between the return to labor, MPL L, and the return to capital, MPK K. That is, under constant returns to scale, ec

10、onomic profit is zero.4. A CobbDouglas production function has the form F(K,L) = AKL1. The text showed that the parameter gives capitals share of income. So if capital earns one-fourth of total income, then = 0.25. Hence, F(K,L) = AK0.25L0.75.5. Consumption depends positively on disposable incomei.e

11、. the amount of income after all taxes have been paid. Higher disposable income means higher consumption. The quantity of investment goods demanded depends negatively on the real interest rate. For an investment to be profitable, its return must be greater than its cost. Because the real interest ra

12、te measures the cost of funds, a higher real interest rate makes it more costly to invest, so the demand for investment goods falls.6. Government purchases are a measure of the value of goods and services purchased directly by the government. For example, the government buys missiles and tanks, buil

13、ds roads, and provides services such as air traffic control. All of these activities are part of GDP. Transfer payments are government payments to individuals that are not in exchange for goods or services. They are the opposite of taxes: taxes reduce household disposable income, whereas transfer pa

14、yments increase it. Examples of transfer payments include Social Security payments to the elderly, unemployment insurance, and veterans benefits.7. Consumption, investment, and government purchases determine demand for the economys output, whereas the factors of production and the production functio

15、n determine the supply of output. The real interest rate adjusts to ensure that the demand for the economys goods equals the supply. At the equilibrium interest rate, the demand for goods and services equals the supply.8. When the government increases taxes, disposable income falls, and therefore co

16、nsumption falls as well. The decrease in consumption equals the amount that taxes increase multiplied by the marginal propensity to consume (MPC). The higher the MPC is, the greater is the negative effect of the tax increase on consumption. Because output is fixed by the factors of production and the production technology, and government purchases have not changed, the decrease in consumption must be offset by a