At a consumer's interior optimum solution, which of the following will not necessarily hold true?
A) $M U _ { x } = M U _ { y }$
B) $\frac { M U _ { x } } { M U _ { y } } = \frac { P _ { x } } { P _ { y } }$
C) $M R S _ { x , y } = \frac { M U _ { x } } { M U _ { y } }$
D) $M R S _ { x , y } = \frac { P _ { x } } { P _ { y } }$

Question

At a consumer's interior optimum solution, which of the following will not necessarily hold true? 
A) $M U _ { x } = M U _ { y }$
B) $\frac { M U _ { x } } { M U _ { y } } = \frac { P _ { x } } { P _ { y } }$
C) $M R S _ { x , y } = \frac { M U _ { x } } { M U _ { y } }$
D) $M R S _ { x , y } = \frac { P _ { x } } { P _ { y } }$

Quizplus · Accepted Answer

At the consumer's interior optimum solution, it is not necessary for the marginal utilities of two goods to be equal. It is only necessary that the ratio of their marginal utilities is equal to the ratio of their prices. This is expressed in option B and D. Option C relates to the marginal rate of substitution, which is equal to the ratio of marginal utilities at the optimum solution. Hence, the correct answer is option A.

At a Consumer's Interior Optimum Solution, Which of the Following MUx=MUyM U _ { x } = M U _ { y }MUx​=MUy​

At a Consumer's Interior Optimum Solution, Which of the Following $M U _ { x } = M U _ { y }$