In: Economics
Meghan’s utility function is given byU( x, y) = x yShe has income I =240 and faces prices Px = $ 4and Py = $ 4 Find Meghan’s optimal basket given these prices and her income. If the price of x decreases to $ 2 and Meghan’s income is unchanged, what must the price of y rise to in order for her to be exactly as well off as before the change in Px? (Hint: You need to calculate p y such that, with the new prices, Meghan reaches exactly the same indifference curve as before).
U(x,y)=xy
Px=$4 , Py=$4 , I=240
Budget equation
I=Px*X+Py*Y
240=4X+4Y
60=X+Y
Optmality is achieved when slope of indifference curve mathces with slope of budget line
MRS=Marginal rate of substitution is the slope of indiffernce curve and calculated as below
MRS=MUx/MUy where MUx=dU/dx=y amd MUy=dU/dy=x
SLope of budget line above is Px/Py
therefoe we have,
MRS=Px/Py
y/x=Px/Py=1
y=x...Equation 1)
Using equation 1) into budget equation we get
60=x+y=2x
x=y=30
Hence the optimal budget is (x,y)=(30,30) & Utility from this budget is U(X,Y)=30*30=900
Now if Price of X decreases to $2 then we need increased Y such that we get same utility
Again using MRS we get
y/x=2/(Py+k)
y=2x/(Py+k)
Using this into new budget equation
240=2X+(Py+k)Y
240=2X+2X
X=60 and Y=120/(Py+k)
Now originally Py=$4 therefore using the same value we get to obtain utility of 900 levels
900=XY=60(120/(4+k))
1/8=1/(4+k)
k=4
hence New Py'=Py+k=4+4=8
we need Px=$2 and Py'=$8 to maintain same utility levels