A monopolist faces a demand curve P = 210 - 4Q and initially faces a constant marginal cost MC = 10.
a) Calculate the profit-maximizing monopoly quantity and compute the monopolist's total revenue at the optimal price.
b) Suppose that the monopolist's marginal cost increases to MC = 20. Verify that the monopolist's total revenue goes down.
c) Suppose that all firms in a perfectly competitive equilibrium had a constant marginal cost MC = 10. Find the long-run perfectly competitive industry price and quantity.
d) Suppose that all firms' marginal costs increased to MC = 20. Verify that the increase in marginal cost causes total industry revenue to go up.