Marginal cost (profit) is the change in total cost (profit) caused by an incremental change in the level of activity (Thomas and Maurice, 2012, p. 95). In these definitions, increment refers to a small change from the total level of activity. Marginal cost is the slope of the total cost curve and marginal benefit is the slope of the total profit curve. The intersection of these two lines on a graph represents the point where net profit is maximized, or the optimal level of