Final answer:
The profit-maximizing level of output is 5 units, as producing more than that would reduce profits. If '5,000' indicated the combined total number of units produced for the three magazines, b) 5,000 might be correct, but considering 5 units each for three different magazines, the total would be d) 1,500.
Step-by-step explanation:
To find the profit-maximizing level of output, we must consider the marginal revenue and marginal cost for each additional unit produced. At an output of 4 units, the marginal revenue is $600 and the marginal cost is $250, which indicates increasing output adds to profits. However, at an output of 5, the marginal revenue equals the marginal cost at $400, meaning profits remain unchanged by producing this unit. Expanding output to 6 results in a marginal revenue of $200 and a marginal cost of $850, causing profits to decrease. Thus, the profit-maximizing level of output for the monopoly, considering profit maximization comes from equating marginal revenue to marginal costs, is 5 units. The information provided does not indicate the specific quantities of each magazine but suggests the optimal total unit production combined is 5 units.
Given that the problem mentions the total number of units produced of all three magazines combined, the likely correct choice based on the provided information is option b) 5,000, assuming that the '5,000' indicates the total number of units for the three magazines combined, as this option aligns with a profit-maximizing level of output being 5 units per type of magazine. However, if each 'unit' in options a), b), and c) represents an individual magazine, then the correct answer would be d) 1,500 as the total number of magazines produced would be 5 units for each of the 3 magazines.