An economy is composed of two individuals, whose demands for a public good - street lighting - are given by P = 12-(1/2)Q and P = 8-(1/3)Q.
(a) Graph these demands on a diagram.
(b) Derive the total demand for this public good by summing the demands vertically, and write down a resulting equation for this demand curve.
(c) Let the marginal cost of providing the good be $5 per unit. Find the efficient supply of the public good in this economy - where the marginal cost equals the total value of a marginal unit.