4. Assume the production function is given by Q = 4K + 8L. Determine the average product of capital when 10 units of capital and 5 units of labor are employed?
a) 3.
b) 4.
c) 7.
d) 8.

7. For the cost function C(Q) = 100 + 2Q + 2Q^2, the marginal cost of producing 2 units of output is
a) 2.
b) 3.
c) 10.
d) 14.

8. Suppose a consumer with an income of $100 who is faced with Px = 1/2 and Py = 1. What is the market rate of substitution between good X (horizontal axis) and good Y (vertical axis)?
a) - ½.
b) -1.
c) -2.
d) -4.