In: Economics
A consumer has an income of $120 to buy two goods (X, Y). the price of X is $2 and the price of Y is $4. The consumer utility function is given by
UX,Y=X2/3*Y1/3
You are also told that his marginal utilities are
MUX=23YX1/3
MUY=13XY2/3
Assume that the price of good X increases to PX'=$8, and holding everything else constant:
Hint: Do not compute and graph point C.
Research studies found the demand for good X as follow:
X=8-0.4*PX+0.2*PY+0.05*M
where, PX is the price of good X, PY is the price of good Y, and M is consumer’s income.
Income(M)= 120
Price of X= Px= 2
Price of Y= Py= 4
Budget line: XPx+YPy=M
4Y= 120-2X
Y= (120-2X)/ 4
Differentiate it wrt X:
dY/dX= -2/4= -1/2 Slope of budget constraint
U=X2/3Y1/3
MUX= (2/3)X-1/3 Y1/3
MUY= (1/3) X2/3Y-2/3
MRS= MUX/MUY= 2Y/X
For optimal bundle:
MRS= Slope of budget constraint
2Y/X= 1/2
X= 4Y Equation 1
Use this equation in Budget line:
2X+4Y=120
2X+X= 120
X= 120/3= 40
Put X=40 in equation 1:
X= 4Y
40/4= Y
Y= 10
Optimal bundle= (40,10)
If Px'= 8:
New budget line: 8X+4Y= 120
Slope of budget line= (-)2
For optimal bundle:
MRS= Slope of budget line
2Y/X= 2
Y=X Equation 2
Use this equation in new budget line:
8X+4Y=120
12X=120
X=10
Y=10
New optimal bundle= (10,10)
X=8-0.4*PX+0.2*PY+0.05*M
With PY=4 and M=120
X= 8-0.4PX+0.8+6
X= 14.8-0.4PX
For X=12:
12= 14.8-0.4PX
0.4PX= 2.8
PX= 7
A consumer is ready to pay price for each= 7 for Quantity of X=12. If PX is less than or equals to 7 then consumer can afford and if price is more than 7 then Consumer can not afford to buy 12 units of good X.