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What is true of marginal cost when the marginal product of labor is increasing? 0 It is positive and decreasing. Q It is negative and decreasing. Q It is positive and has a constant slope. Q It is negative and increasing. 0 It is positive and increasing. If average total cost is declining, then: 0 marginal cost must be greater than average total cost. 0 marginal cost must be less than average total cost. 0 the average xed cost curve must lie above the average variable cost curve. 0 total cost must also be declining. Which of the following best expresses the law of diminishing marginal productivity? 0 Adding an additional worker adds no additional output 0 Because large-scale production allows the realization of economies of scale, the real costs of production vary directly with the level of output 0 Proportional increases in a variable input result in a less than proportional increase in total output 0 Proportional increases in the inputs of all resources results in a less than proportional increase in total output Suppose a professor gives up her teaching job to devote her time to writing textbooks. If salaries of professors then rise, 0 her explicit costs as an author will rise. 0 her economic prot as an author will fall 0 her accounting prot as an author will fall. 0 all of these answers are correct. Marginal cost: 0 is the difference between total cost and total variable cost. 0 declines continuosly as output increases. 0 rises for a time, but then begins to decline when diminishing returns set in. 0 equals both average variable cost and average total cost at their respective minimums