consider the following open economy. the real exchange rate is fixed and equal to 1. consumption is given by C=50+0.5(Y-T), investment is I =20, taxes are t=10, and the government budget is balanced. imports and exports are given by I M = 0.2Y and X = 0.02Y* where Y* is foreign GDP.
(a)
"Y=C+I+G+NX"
"Y=50+0.5(Y-10)+20+10+(0.02Y^*-0.2Y)"
"Y=75+0.5Y+0.02Y^*-0.2Y=75+0.3Y+0.02Y"
"Y=\\frac{(75+0.02Y^*)}{0.7}"
(b)
Government purchase multiplier:
"=\\frac{1}{1-mpc+mpm}"
"=\\frac{1}{(1-0.5+0.2)}=\\frac{1}{0.7}=1.43"
If there is no import and export, the the government purchase multiplier:
"=\\frac{1}{1-mpc}=\\frac{1}{(1-0.5)}=2."
(c)
If "Y^*=10Y"
So,
"Y=\\frac{(75+0.02\\times 10Y)}{0.7}"
"\\implies Y=150"
So, "Y^*=150\\times10=1500"
Foreign GDP after adverse demand hit:
"=0.9\\times1500=1350"
New domestic GDP:
"=0.1\\times1350=135"
So, domestic GDP falls by 10%.
(d)
Government purchase multiplier"=\\frac{1}{0.7}=1.43"
Required increase in output = 15.
Required increase in government purchases:
"=\\frac{15}{0.7}=21.42"
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