It is usually assumed that a perfectly competitive firm's supply curve is given by its marginal cost curve. In order for this to be true, which of the following additional assumptions are necessary? I. That the firm seeks to maximize profits. II. That the marginal cost curve be positively sloped. III. That price exceeds average variable cost. IV. That price exceeds average total cost

What is the key incentive that motivates a manufacturer to sell its products?

a. making profits on sales b. pleasing the consumer c. putting others out of business d. popularity of the product

In a world of perfect certainty, sharecropping would be less efficient than a farm owner working his own farm because

(a) sharecroppers receive only half of their marginal product. (b) paying a worker a wage gives him or her an incentive to shirk. (c) sharecroppers are exploited by landlords. (d) renting farmland concentrates risk on the renters. (e) all of the above.