Solution
David answered on
Dec 20 2021
1
1. Consider the following IS-LM model:
C = 200 + .25YD
I = 150 + .25Y - 1000i
G = 250
T = 200
(M/P)d = 2Y - 8,000i
i = i0 = 0.05
a. Derive the IS relation. (Hint: You want an equation with Y on the left side, all else
on the right.);
Equation of IS curve:
Y=C+I+G
C=C(Y-T)
So, we have,
Y=200+(.25*(Y-200))+150+.25Y-1000i+250
Or, Y=600-50+(.25+.25)Y-1000i
Or, Y(1-.5)=550-1000i
Or, Y=(550-1000i)/.5
Or, Y=1100-2000i
. Derive the LM relation. (Hint: It will be convenient for later use to rewrite this
equation with i on the left side, all else on the right.)
Equation of LM curve:
(M/P)=M/Pd
Or, M/P=2Y-8000i
Or, 8000i=2Y-M/P
This is the required LM curve where, M/P=real money balance.
c. Solve for equili
ium real output. (Hint: Substitute the value for the interest rate
into the IS equation and solve for output.)
Equation of IS curve:
Y=1100-2000i
for i=.05, Y=(1100-(2000*.05))=1000
d. Solve for the equili
ium real money supply. (Hint: Substitute the value you
obtained for Y in [c] into the LM equation and solve for M/P.)
Equation of LM curve:
M/P=2Y-8000i
For Y=1000,i=.05
M/P=(2*1000)-(8000*.05)= 1600
e. Solve for the equili
ium values of C and I and verify the value you obtained for Y
y adding up C, I, and G.
C=200+(.25*(1000-200))=400
I=(150+(.25*1000)-(1000*.05))=350
G=250
So, C+I+G=(400+350+250)=1000
Thus, the equality between C+I+G and Y is verified.
f. Now suppose that the interest rate, i0 was cut to 3% (i.e. 0.03). Solve for Y, M/P, C,
and I, and describe in words the effects of an expansionary monetary policy.
Equation of IS curve:
Y=1100-2000i
for i=.03, Y=(1100-(2000*.03))=1040
Equation of LM curve:
M/P=2Y-8000i
For Y=1040,i=.03
M/P=(2*1040)-(8000*.03)= 1840
C=200+(.25*(1040-200)) =410
I=(150+(.25*1040)-(1000*.03)) =380
As, following a decrease in rate of interest, C,Y and I has increased, we can conclude that expansionary monetary policy leads to increase in national income, consumption and saving of the economy....