1. The ratio of total productivity to the total quantity of a variable input being used in production is

a. equal to marginal physical productivity of the input.

b. constant as employment levels of the input vary.

c. equal to average physical productivity of the input.

d. equal to the marginal rate of technical substitution.

2. Which one of the following statements is false?

a. In the long run all production inputs are variable.

b. Decreasing returns to scale prevail when output increases by a proportion that is smaller than the proportion by which all inputs increase.

c. When marginal cost equals average variable cost, average variable cost is at its minimum.

d. Average fixed cost curve can have a U-shape