Question

宏观经济学题目求解。md = (1/4)Y - 10i and ms = 400. 求详细解答过程。

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•Assume the money sector can be described by the following two equations: md = (1/4)Y - 10i and ms = 400. In the expenditure sector only investment spending (I) is affected by the interest rate (i), and the equation of the IS-curve is: Y = 2,000 - 40i. •a. Assume the size of the expenditure multiplier is a = 2. What is the effect of an increase in government purchases by DG = 200 on income and the interest rate? •b. Can you determine how much investment is crowded out as a result of this increase in government purchases? •c. If the money demand equation were changed to md = (1/4)Y, how would your answers in a. and b. change?

Answer 1

政府支出增加前的均衡：Y=2000-40i ， 400=Y/4-10i Y=1800 i=5
a. 政府支出增加200，乘数为2，所以单纯的乘数效应是收入增加200*2=400
新的均衡是Y=2400-40i ， 400=Y/4-10i Y=2000 i=10
收入效应增加2000-1800=200，利率效应提高=10-5=5
b. 挤出效应是400-200=200，即由于利率的提高，投资减少，挤出收入200，没有达到400
c.如果md=Y/4，意味着财政支出引致的收入增加只会增加货币需求和供给，不会改变利率，投资不会减少，这样挤出效应为0，收入效应增加400，利率不变。

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