When the private costs and the social costs are NOT the same, there is a(n)

A firm earns an operating profit if

a. price equals marginal cost. b. revenues exceed variable costs of production. c. price is less than average variable costs of production d. revenues equal fixed costs.

The rate of technological progress is an important determinant of ________

A) long-run variation in economic growth B) long-run increases in interest rates C) short-run variation in employment rates D) short-run variation in economic growth