See below: An economy has the following AD and AS curves: AD curve: Y = 700 + 40
ID: 1098565 • Letter: S
Question
See below:
Explanation / Answer
AD Curve: Y = 700 + 40(M/P)
AS Curve: Y = Y(bar) + [10 x (P - Pe)]
Given Y(bar) = 1500, M = 800, and Pe = 40.
Then using the values above in AD and AS curve, we get
AD: Y = 700 + 40(800/P) => Y = 700 + 32000/P
AS: Y = Y(bar) + [10 x (P - Pe)] => Y = 1500 + 10*(P - 40) = 1500 + 10P - 400 => Y = 1100 + 10P
a) At equilibrium, AD = AS
Equaling Y across the above AD and AS equation we get
700 + 32000/P = 1100 + 10P
=>32000/P - 10P = 400
=> 32000 - 10P^2 = 400P
=> P^2 + 40P - 3200 = 0
=> P^2 + 80P - 40P - 3200 = 0
=> P(P + 80) - 40(P + 80) = 0
=> (P+80)(P-40) = 0
=> P = -80 or P = 40
But as prices cannot be negative, we have equilibrium P = 40
Equilibrium Output Y = 1100 + 10P = 1100 + 10*40 = 1100 + 400 = 1500
b) In this case M increases to 924, while all other values remain the same
Using the approach above, we get
AD: Y = 700 + 40(924/P) => Y = 700 + 36960/P
AS: Y = Y(bar) + [10 x (P - Pe)] => Y = 1100 + 10P
At equilibrium, AD = AS
Equaling Y across the above AD and AS equation we get
700 + 36960/P = 1100 + 10P
=>36960/P - 10P = 400
=>36960 - 10P^2 = 400P
=> 3696 - P^2 = 40P
=> P^2 + 40P - 3696 = 0
=> P^2 + 84P - 44P - 3696 = 0
=> (P + 84)(P - 44) = 0
=> P = -84 or P = 44
But as prices cannot be negative, we have equilibrium P (short-run) = 44
Equilibrium output Y (short-run) = 1100 + 10P = 1100 + 10*44 = 1100 + 440 = 1540