A firm has an average total cost of $50. If it sells 20 units of its product at $80 each, what is its profit?

The union participation rate in the United States is

a. lowest among service workers in the private sector b. highest among service workers in the private sector c. lowest among service workers in the public sector d. highest in heavy industry e. highest in high-technology industries

When positive externalities are present in a market, it means that:

A. private benefits are less than social benefits. B. private benefits are less than external benefits. C. social benefits are less than external benefits. D. external benefits are equal to social benefits.