In: Economics
At the equilibrium consumption bundle, which of the following holds?
MRSX,Y = PY/PX.
MRSX,Y = −PX/PY.
MRSX,Y = PX/PY.
MRSX,Y = −PY/PX.
Answer Option 3 MRSxy=Px/Py
Explanation:
Suppose there are two goods X and Y
Price of good X =Px
Price of good Y = Py
Marginal rate of substitution (MRS) is the rate at which the consumer is substituting one good with another good, therefore MRSxy=∆Y/∆X=MUx/MUy
Slope of the price line = Price of good X/ price of good Y = Px/Py
At equilibrium consumption bundle or utility maximising combination the marginal rate of substitution (MRS) must be equal with the slope of the price line, therefore at equilibrium combination, MRSxy= Price of X/ Price of Y
At equilibrium combination, MRSxy= Px/ Py therefore Option 3 is true
Slope of price line cannot be Py/Px, therefore option 1 is not true
Slope of price line cannot be negative, like -Px/Py and –Py/Px because price line does not shows any trade off. It only shows the possible combination that the consumer can afford with his given budget. Therefore option 2 and option 4 is not true