1)The utility that a consumer obtains by consuming goods A and B is given by U(Qa,Qb)= Qb^0.1Qa^0.1.

a)With the assumption that Pb=6 and Pa=10, Y = 100, calculate the optimal Qa and Qb .
Determine the MRSba at the optimum level.

1 answer

To find the optimal quantity of goods A and B, we need to maximize the utility function U(Qa, Qb) subject to the budget constraint.

The budget constraint is given by: PbQb + PaQa = Y
Substituting the given values: 6Qb + 10Qa = 100

To solve for the optimal quantities, we can use the Lagrange Multiplier method. We set up the following equation:

L(Qa, Qb, λ) = U(Qa, Qb) - λ(PbQb + PaQa - Y)

Taking the partial derivatives of L with respect to Qa, Qb, and λ:

∂L/∂Qa = 0.1Qb^0.1 * 0.1Qa^-0.9 - λPa = 0 (1)
∂L/∂Qb = 0.1Qa^0.1 * 0.1Qb^-0.9 - λPb = 0 (2)
∂L/∂λ = -(PbQb + PaQa - Y) = 0 (3)

Solving equations (1) and (2) simultaneously, we can find the values of Qa and Qb:

0.1Qb^0.1 * 0.1Qa^-0.9 - λPa = 0
0.1Qa^0.1 * 0.1Qb^-0.9 - λPb = 0

0.01Qb^0.1 * Qa^-0.9 = λPa
0.01Qa^0.1 * Qb^-0.9 = λPb

Dividing the two equations:

(Qb/Qa)^0.1 = (Pa/Pb)

Taking both sides to the power of 10:

Qb/Qa = (Pa/Pb)^10

Now we substitute the given values: Pa = 10 and Pb = 6

Qb/Qa = (10/6)^10
Qb/Qa = (5/3)^10

Taking the 10th root of both sides:

Qb/Qa = (5/3)^1

Now, we solve for Qb/Qa:

Qb/Qa = 5/3

We can rewrite the budget constraint as:

6Qb + 10Qa = 100
Qb = (100 - 10Qa)/6

Substituting Qb/Qa with 5/3:

(100 - 10Qa)/6 = (5/3)Qa

Multiplying both sides by 6 to remove the denominator:

100 - 10Qa = 10Qa

Simplifying:

20Qa = 100

Dividing by 20:

Qa = 5

Plugging Qa = 5 into the budget constraint:

Qb = (100 - 10(5))/6
Qb = 5/3

So, the optimal quantities are Qa = 5 and Qb = 5/3.

To find the MRSba at the optimum level, we need to find the marginal utility of A (MUa) and the marginal utility of B (MUb) and take the ratio:

MUa = ∂U/∂Qa = 0.1Qb^0.1 * 0.1Qa^-0.9
MUa = 0.1(5/3)^0.1 * 0.1(5)^-0.9

MUb = ∂U/∂Qb = 0.1Qa^0.1 * 0.1Qb^-0.9
MUb = 0.1(5)^0.1 * 0.1(5/3)^-0.9

MRSba = MUa / MUb
MRSba = [0.1(5/3)^0.1 * 0.1(5)^-0.9] / [0.1(5)^0.1 * 0.1(5/3)^-0.9]