Profit Maximization - Marginal Revenue-marginal Cost Perspective

Marginal Revenue-marginal Cost Perspective

An alternative perspective relies on the relationship that, for each unit sold, marginal profit (Mπ) equals marginal revenue (MR) minus marginal cost (MC). Then, if marginal revenue is greater than marginal cost at some level of output, marginal profit is positive and thus a greater quantity should be produced, and if marginal revenue is less than marginal cost, marginal profit is negative and a lesser quantity should be produced. At the output level at which marginal revenue equals marginal cost, marginal profit is zero and this quantity is the one that maximizes profit. Since total profit increases when marginal profit is positive and total profit decreases when marginal profit is negative, it must reach a maximum where marginal profit is zero - or where marginal cost equals marginal revenue - and where lower or higher output levels give lower profit levels. In calculus terms, the correct intersection of MC and MR will occur when:

The intersection of MR and MC is shown in the next diagram as point A. If the industry is perfectly competitive (as is assumed in the diagram), the firm faces a demand curve (D) that is identical to its marginal revenue curve (MR), and this is a horizontal line at a price determined by industry supply and demand. Average total costs are represented by curve ATC. Total economic profit are represented by the area of the rectangle PABC. The optimum quantity (Q) is the same as the optimum quantity in the first diagram.

If the firm is operating in a non-competitive market, changes would have to be made to the diagrams. For example, the marginal revenue curve would have a negative gradient, due to the overall market demand curve. In a non-competitive environment, more complicated profit maximization solutions involve the use of game theory.