Returns to scale refers to the change in output when

For a monopolist:

a. price equals average total cost. b. price is above marginal revenue. c. marginal revenue equals zero. d. marginal cost equals zero. e. average total cost equals marginal cost.

Which of the following is not something that John Maynard Keynes used to describe an economist? a. He must be a mathematician, historian, statesman, and philosopher in some degree. b. He must understand symbols and speak in words

c. He must only contemplate in abstract and general terms. d. He must study the present in light of the past for purposes of the future.