3) [2 points] Suppose that buyers cannot distinguish between perfect and defective joints, so that there is just one market for mechanical joints of uncertain quality. What is the supply curve for joints? What is the quality of the joints supplied at different prices? 4) [3 points] Buyers cannot distinguish between perfect and defective joints but they are sophisticated: they understand the supply curve and the quality of the joints for sale at different prices. Determine the equilibrium of the joint market. What is the equilibrium price? How many joints are sold in equilibrium, and of what quality? What are the profits of high and low quality firms