Final answer:
Profit maximization occurs where marginal revenue equals marginal cost (MR=MC), at a specific level of output rather than a range. This is true for both perfectly competitive firms and monopolists, as it determines the most profitable quantity to produce.
Step-by-step explanation:
Profit maximization for a firm, whether it is perfectly competitive or a monopolist, takes place on a specific portion of the demand curve. This occurs where marginal revenue (MR) is equal to marginal cost (MC). For a perfectly competitive firm, profit maximization will occur at the level where MR equals MC, which can be shown on a graph as a specific point. For instance, if MR=MC is true at Q=80 units, that is the profit-maximizing output level. However, a monopolist may also utilize this approach taking into account the demand curve and marginal revenues to find the profit-maximizing quantity, often using experiences from modest changes in output as it can be difficult to determine the entire total revenue for dramatic changes in production.
The profit-maximizing level of output is not a range but a specific point. It's the last possible output level where marginal revenue is greater than or equal to marginal cost before it starts to fall. In other words, stopping the production at the point where MR=MC ensures the firm maximizes its profits.