Question 43

Firms can earn economic profits in the short run and maximum profit occurs when marginal revenue equals marginal cost.

Both monopolies and monopolistic competition allow firms to earn economic profits in the short run due to the lack of perfect competition. Additionally, in all three market structures, maximum profit is achieved when marginal revenue equals marginal cost, highlighting a shared characteristic in profit maximization.

A) The price of a unit is greater than the marginal cost.

This statement does not apply universally across all three market structures. While monopolies may have prices greater than marginal costs, perfect competition results in prices equal to marginal costs. Therefore, this option fails to accurately reflect a shared feature of the three market types.

B) The firm(s) can earn economic profits in the short run.

This option is correct as it applies to monopolies and monopolistic competition, where firms can set prices above average costs to achieve economic profits in the short run. Perfect competition, however, only allows for normal profits in the long run, making this characteristic a shared feature only in specific contexts.

C) The structure does not produce welfare-maximizing level of output.

While it is true that monopolies and monopolistic competition may not achieve the welfare-maximizing level of output, perfect competition does reach this level as it produces at the point where price equals marginal cost. Therefore, this option is not universally applicable.

D) In the long run new firms can easily enter the market.

This statement is incorrect for monopolies, where barriers to entry prevent new firms from entering the market easily. While it applies to perfect competition and monopolistic competition, it does not represent a shared characteristic among all three structures.

E) In the long run, it is nearly impossible for new firms to enter.

This option accurately describes monopolies but does not apply to perfect competition or monopolistic competition, where entry is relatively easier. Thus, it does not represent a shared feature across all three market structures.

F) Maximum profit occurs when marginal revenue equals marginal cost.

This statement is correct for all three market structures. Firms in monopolies, monopolistic competition, and perfect competition all maximize profits by producing at the quantity where marginal revenue equals marginal cost, making it a shared characteristic.

Conclusion

The correct answers, B and F, highlight key features shared by monopolies, monopolistic competition, and perfect competition. While firms can earn economic profits in the short run, all three structures also utilize the principle that maximum profit occurs when marginal revenue equals marginal cost. Other options fail to represent characteristics applicable to all three market types consistently.