4. There are three consumers of a public good. The demands for consumers are as [50-G if G50 110-G if G110 follows: P 0 if G> 50 P = 0 if G > 110* 150-G if G150 P3 , where G measures the number of units of the good and p 0 if G > 150' the price in dollars. The marginal cost of the public good is $190. (a) What is the optimal level of the public good? Illustrate your answer with a graph. (Hint: Use the Samuelson condition.) (b) Explain why the public good may not be supplied at all. (Hint: Recall the free-rider problem.) (c) If the public good is not supplied at all, what is the size of the efficiency loss arising from this market failure?