Consider the following Marginal Private Cost (MPC), Marginal Social Cost (MSC) and market demand curves. These curves relate to a market for a product, the production of which generates a negative externality. Use these equations to answer the questions from a) to e). In answering questions a) to e) make sure that you also use a fully labelled and explained diagram.

MPC = 10 + 10Q

MSC = 10 + 12 Q

P = 70 - 5Q

a. What is the private market equilibrium P and Q?

b. What is the socially efficient equilibrium P and Q?

c. Explain in words why the equilibrium in a) is not efficient. Explain in words why the equilibrium in b) is efficient.

d. Calculate the deadweight loss from the negative externality in this scenario.

e. What is the size of the Pigovian Tax required to produce the efficient equilibrium? How much revenue would the government collect if it imposes this tax?

f. Explain in words how a system of marketable permits differs from the Pigovian Tax as a way to correct for the inefficiency associated with the negative externality. Why do economists tend to prefer a system of marketable permits over the Pigovian Tax? There is no need to use a diagram in your answer to f).