In the loanable funds market model, the demand curve represents:

A firm that can sell its output for $40 per unit. When it increases its labor force from 4 workers to 5 workers its output increases from 15 to 17 units. The value of marginal product of the 5th worker is

A) $680. B) $340. C) $80. D) $40.

The real-income effect refers to

A) the law of diminishing marginal utility. B) the want-satisfying power of a good or service. C) substitution of less expensive commodities for more expensive commodities. D) the change in purchasing power when the price of a good changes.