The Marginal Revenue Product CurveThis curve shows how the marginal revenue product of labor depends on the number of workers employed. It slopes downward because of diminishing returns to labor in production. To maximize profit, George and Martha choose the level of employment at which the marginal revenue product of labor is equal to the market wage rate. For example, at a wage rate of $200 the profit-maximizing level of employment is 5 workers, shown by point A. The marginal revenue product curve of a factor is the firm’s individual demand curve for that factor.