In: Economics
Jacinto consumer two goods: A and B, his preferences can be represented by the Cobb-Douglas function: U (XA, XB) = 2XA * XB2, where XA represents the units consumed of good A and XB the units consumed of good B. Consider generic prices for the goods PA, PB and an income of m
A) Find Jacinto's demand functions for good A and B
B) if PA = 60, PB = 90 and m = 540:
i. What are the optimal quantities of goods A and B that Jacinto should consume?
ii. What is the maximum utility that Jacinto can obtain?
iii. Represent graphically the optimal choice of Jacinto
U = 2XA.XB2
Budget line m = PA.XA + PB.XB
(A) Utility is maximized when MRS = MUA / MUB = PA / PB
MUA = U / XA = 2XB2
MUB = U / XB = 4XA.XB
MUA / MUB = XB / 2XA = PA / PB
2PA.XA = PB.XB
Substituting in budget line,
m = PA.XA + 2PA.XA = 3PA.XA
XA = m / 3PA
Again,
m = (PB.XB / 2) + PB.XB = (3/2).PB.XB
XB = 2m / 3PB
(B)
(i) XA = 540 / (3 x 60) = 3 and XB = (2 x 540) / (3 x 90) = 4
(ii) U = 2 x 3 x (4)2 = 6 x 16 = 96
(iii) Budget line: 540 = 60XA + 90XB, or 18 = 2XA + 3XB [Dividing by 30]
When XA = 0, XB = 18/3 = 6 (Vertical intercept) and when XB = 0, XA = 18/2 = 9 (Horizontal intercept)
In following graph, AB is the budget line and IC0 is the indifference curve tangent to AB at point E with optimal quantity of XA being XA0 (= 3) and quantity of XB being XB0 (= 4).