Question: Economists have long known that free markets are perfectly efficient. Consider Q1 in the graph, above. How much do consumers value one more unit of output (Q1 + 1)? How much do producers value one more unit of output? Use the concepts of consumer surplus and producer surplus to explain why Q2 is more efficient than Q1. Now use the concept of total economic surplus to explain why the equilibrium quantity is the most efficient. Why would Q4 be less efficient than the equilibrium quantity?
