Question: (Requires calculus) A monopolist with constant marginal costs of $20 serves two separate markets, where demands are
QA = 100 - PA, and
QB = 140 - 2PB
Add the demands and find the optimal output and uniform price if the markets cannot be separated. What is elasticity of demand at this price and quantity? Graph the total demand, marginal costs, and marginal revenue, and explain the shape of marginal revenue. (Note that demand has an angle in it at a price of $100.) Now allow the seller to set different prices in A and B. Find those prices, along with the quantities sold and elasticities of demand. Is total output greater than in the case of a single price? Using the previous demand curve from Market A, find an example in which the demand curve in Market B is low enough and elastic enough that it does not pay a single-price monopolist to sell any output at all in Market B, but it does pay a price discriminator to do so. Now is the discriminating monopolist's output greater than if it had charged a uniform price?