Consider two consumers of a product A & B with an individual demand function Qa = 400 - 5P and Qb = 300 - 2.5Pb respectively where the price in dollars and Q is the quantity demanded.

1. Obtain and analyse the marginal social benefit function if the product is a public good. Support your answers with a suitable diagram.

1. If the marginal cost of producing the public good is $10, compute the optimal quantity of the public good. How will your answer be different if the marginal cost is $30 instead?