Consider a production function Q = 3K + 4L, when L is graphed on the x-axis and K is graphed on the y-axis, the marginal rate of technical substitution is equal to
A) 4/3 and the isoquant is convex to the origin.
B) 4/3 and the isoquant is a straight line.
C) ¾ and the isoquant is a straight line.
D) 12 and the isoquant is convex to the origin.

Question

Quizplus · Accepted Answer

The marginal rate of technical substitution (MRTS) is equal to the absolute value of the slope of an isoquant. It represents the rate at which one input can be substituted for another without changing the level of output. 
Using the given production function, we can calculate the MRTS as the ratio of the marginal product of labor to the marginal product of capital:
MRTS = MPL/MPK = 4/3
The isoquant shows all combinations of K and L that produce a given level of output. In this case, Q = 3K + 4L. The slope of the isoquant is -(dK/dL), which is equal to -MPL/MPK. Since MPL/MPK is constant (equal to 4/3), the slope of the isoquant is constant (and negative). This means that the isoquant is a straight line. 
Therefore, the answer is B: 4/3 and the isoquant is a straight line.

Consider a Production Function Q = 3K + 4L, When