The figure to the right depicts both monopolistically competitive and perfectly competitive firms. In what fundamental ways do these two types of firms behave similarly in a long-run equilibrium? In what fundamental ways does the monopolistically competitive firm behave differently? Part 2 Key similarities are that both the monopolistically competitive firm and the perfectly competitive firm face competition from few many other firms, produce at the point where MR < MC MR = MC MR > MC , and have a price larger than less than equal to average total cost and hence earn zero negative positive economic profits in a long-run equilibrium. Part 3 The key differences are that the demand curve for the monopolistically competitive firm slopes downward because of product differentiation homogeneity , and that its price is less than exceeds equals MR but equals but is less than and exceeds the minimum feasible ATC