A firm is considering selling a new good at an introductory price that is less than the monopoly price. By doing so, it hopes to create a critical mass of users and benefit from an increased future demand generated by a positive network externality for the product. The marginal cost of production is constant at \(M C=4\) and equal to the average cost. The inverse demand curve for the product is \(p=20-4 Q\).

a. If the firm were to charge the monopoly price, what would its total profits be over two periods?

b. If the firm tried to take advantage of the positive network externality by instead charging the competitive price in the first period and the monopoly price in the second period, by how much would the demand curve have to rotate outward (that is, its slope has to change) before the firm's total profits over the two periods exceeded your answer to part a?