1. PERFECTLY COMPETITIVE MARKETS

2. Definition of a Perfectly Competitive Market Very Large Number of Sellers and Buyers Identical (Homogeneous) Product Easy Entry/Easy Exit Perfect Information

3. Definition of a Perfectly Competitive Market A.Very Large Number of Sellers –Each firm produces an extremely small percent of total market supply. B.Identical Product –The product sold by one firm is identical to that sold by another firm.

4. Definition of a Perfectly Competitive Market Cont ’ C.Easy Entry and Easy Exit - E asy to enter this industry because costs are low. - A lso easy to quit this industry because of the low costs. D.Buyers and Sellers Have Perfect Information - A ll the buyers and sellers know all of the relevant information.

5. Consequences of a Competitive Market for the Firm A.The Competitive Firm Is A Price Taker - The firm must take the market price as given. B.The Competitive Firm Has No Market Power - The firm is so small that it has no power to shape the market in any way.

6. Consequences of a Competitive Market for the Firm Cont’ C.The Competitive Firm Has A Horizontal Demand Curve –The firm must take the market price as given, and then decide how much it can produce. –It can sell any level of output, but only at the market price. –Whatever levels of output it sells at, the price will stay the same.

7. The Profit Maximizing Rate of Output We wish to answer the question: –At what rate of output will a competitive firm maximize its profits?

8. There Are Two Approaches to Answer This Question A.Total Revenue/Total Cost B.Marginal Revenue/Marginal Cost

9. Total Revenue Total Revenue = - Price times Sales or - Price times Output

10. Average Revenue Average Revenue = –Same as price for the competitive firm.

11. Marginal Revenue Marginal Revenue= - The change in total revenue that comes from selling one more unit of output.

12. Total Revenue/Total Cost Approach Total Profits = Total Revenue - Total Costs Total Revenue = Price * Output = Price * Sales Total Costs = Fixed Costs + Variable Costs

13. Total Revenue/Total Cost Approach Firms maximize profits where total revenues are larger than total costs by the largest amount.

14. The Marginal Cost/ Marginal Revenue Approach More important than the total cost total revenue approach This is because firms use the approach to determine exactly what level to produce at.

15. Recall That: Marginal Revenue = - Change in total revenue from one more sale.

16. Marginal Cost Marginal cost will be defined as: - Change in total cost from one more sale.

17. The Marginal Cost-Marginal Revenue Approach Cont’ The approach is to examine each sale to determine whether the costs of production is less than, equal to, or greater than, the revenues generated from the sale of that unit.

18. Profit Maximization, Marginal Cost/Marginal Revenue Approach If a new sale from a new level of production generates more revenues than costs, the firm should produce at the new level. In this case marginal revenue is greater than marginal cost.

19. Profit Maximization, Marginal Cost/Marginal Revenue Approach If a new sale from a new level of production generates more costs than revenues, the firm should not produce at the new level. In this case marginal cost is greater than marginal revenue.

20. Profit Maximization for the Competitive Firm Cont’ Firms will expand output as long as: MR>MC Firms will cut back output as long as: MC>MR Firms will maximize profits at the output: Where MC=MR

21. SHORT RUN PROFITS AND LOSSES

22. Short Run Profits and Losses A.As long as price is greater than the minimum average total cost, the firm has profits. P > MIN ATC

23. Short Run Profits and Losses B.The break-even price is the price that is equal to the minimum ATC curve. P = MIN ATC

24. Short Run Profits and Losses Cont’ C.If price falls below minimum ATC, it will suffer losses. P < MIN ATC

25. THE SHUT DOWN DECISION

26. Short Run Profits and Losses: The Shut Down Price A.If a firm shuts down, it will suffer a loss equal to its fixed costs. Investors lose all of their money. B.As long as the firm can pay for some of its fixed costs, it should continue to produce.

27. Short Run Profits and Losses: The Shut Down Price C.The shut down price is the price that is just equal to the minimum average variable cost. P = MIN AVC

28. Short Run Profits and Losses: The Shut Down Price Cont’ D.At any price above the minimum average variable cost, the firm will lose money, but less money than if it shuts down. At any price below the minimum average variable cost, the firm should shut down.

29. Summary of Price Decisions If P > MIN ATC, there will be profits. Produce where MR=MC If P = MIN ATC, the firm will break even. Produce where MR=MC

30. Summary of Price Decisions Cont’ If P MIN AVC there will be losses. Produce where MR = MC If P < MIN ATC, and P < MIN AVC then shut down.

31. LONG RUN SUPPLY

32. Constant-Cost Industries An industry in which expansion or contraction will not affect resource prices. Therefore production costs will stay the same.

33. Increasing-Cost Industry An industry in which expansion will lead to a rise in resource prices and production costs; and contraction leads to a fall in resource prices and production costs

34. Decreasing-Cost Industry An industry in which expansion will lead to a fall in resource prices and production costs; and contraction leads to a rise in resource prices and production costs.

35. TOTAL PRODUCT FIXED COSTS VARIABLE COSTS TOTAL COSTS MARGINAL COSTS AVG. FIXED COSTS AVG. VARIABLE COSTS AVG. TOTAL COSTS 0150 1350 2510 3630 4710 5750 6930 71130 81350 91590 101850 1)Compute all costs 2)If price is $186, compute revenues and profit max. level of output. 2)If price is $136, compute revenues and profit max. level of output. 2)If price is $106, compute revenues and profit max. level of output.