6. Short-run supply and long-run equilibrium Consider the competitive market for copper. Assume that, regardless of how many firms are in the industry, every rm in the industry is identical and faces the marginal cost (MC), average total cost (A10), and average variable cost (AVG) curves shown on the following graph. ('8 100 90 so 70 60 50 40 ATC 30 COSTS (Dollars per pound) 20 10 MC AVG 0 10 20 30 40 50 60 70 80 90 100 QUANTITY (Thousands of pounds) 100 Supply (10 firms) 80 70 60 Supply (15 firms) 50 PRICE (Dollars per pound) 40 Supply (20 firms) Demand 30 20 10 0 125 250 375 500 625 750 875 1000 1125 1250 QUANTITY (Thousands of pounds) If there were 10 firms in this market, the short-run equilibrium price of copper would be $ per pound. At that price, firms in this industry would . Therefore, in the long run, firms would the copper market. Because you know that competitive firms earn economic profit in the long run, you know the long-run equilibrium price must be $ per pound. From the graph, you can see that this means there will be _ firms operating in the copper industry in long-run equilibrium