1. Profit Maximization Ed. 7: Ch. 8, pgs 264-265, pgs 277-300 Ed. 6: Ch. 8, pages 265-266, pgs 278-304 1

2. Profit Maximization assuming: 1. Firm must charge every consumer the same price (i.e., no price discrimination) 2. No Strategic Interaction among Firms We will consider two industry structures: Monopoly Monopolistic Competition 2

3. Profit Maximization Example QFCVCTCAFCAVCATCMC 01000 - - - 50 11005015010050150 30 210080180504090 20 3100 20033.333.3366.7 10 41001102102527.552.5 20 5100130230202646 3

4. QFCVCTCAFCAVCATCMC 5100130230202646 30 610016026016.726.6743.3 40 710020030014.328.5742.9 50 810025035012.531.2543.8 60 910031041011.134.4445.6 70 10100380480103848 4

5. What output maximizes profits if the marginal revenue (MR) for each unit the firm sells is $55? What are these profits? 8 55*8-43.75*8=90 5

6. What output maximizes profits if the marginal revenue for each unit the firm sells is $35? What are these profits? 6 35*6-43.33*6=-50 Produce an output of 6 in short- run if fixed costs are sunk. 6

7. What output maximizes profits if the marginal revenue for each unit the firm sells is $25? What are these profits? 5? 25*5-46*5=-105 Better off producing 0 so profits=-FC=-100 7

8. Short-Run Profit Maximizing Rule Produce at an Output where Marginal Revenue = Marginal Cost (MR) (MC) if Total Revenue > Variable Cost [When the firm cannot price discriminate, this is the same thing as saying as long as Price > AVC (from P*Q > AVC*Q) ] 8

9. Monopoly Characteristics 1. There is a single seller 2. There are no close substitutes for the good 3. There are extremely high barriers to entry 9

10. Natural Monopoly (type of monopoly where there exists large economies of scale) Quantity0 $/unit Long Run Average Total Cost ATC one big firm ATC 1/2 big firm Q big firm Q 1/2 big firm when a single firm can supply a good or service to an entire market at a smaller cost than could two or more firms. 10

11. Monopolist Marginal Revenue (with no price discrimination) PQTRMR 1000 919 8216 7321 6424 5525 4624 3721 2816 199 0100 +7 +5 +3 +1 -3 -5 -7 -9 +9 MR Q Note that Marginal Revenue for a given unit is plotted at the midpoint of that unit. 11

12. Use Calculus to Obtain MR curve for Linear Demand Curve Demand Curve: P=a-bQ TR = (a-bQ)Q =aQ-bQ 2 MR =ΔTR/ ΔQ =∂TR/ ∂Q =a-2bQ [In prior graph, a=10 and b=1] Slope of D Slope of MR 12

13. Monopoly If the firm’s goal were to maximize total revenue, where would it produce? The elastic and inelastic portions of the demand curve are labeled. How do these relate to MR? P=$5;  D =-1; TR=$25 Elastic: MR>0 Inelastic: MR<0 Will a monopolist ever produce on the inelastic portion of the demand curve? No. Elastic Inelastic Q MR 13

14. Own Price Elasticity of Demand PtQP dd TR A012-∞-∞ B110-5 C28-2 D36 E44-1/2 F52-1/5 G600 0 10 16 18 16 10 0 MR 10 6 2 -2 -6 -10 14 TR

15. MATH BEHIND: Maximizing Revenue and Own Price Elasticity equaling -1 Max Q TR = Max Q P(Q)Q so Own Price Elasticity of Demand 15

16. Monopoly Maximizing Profits If the monopolist maximizes profits, where would it produce? At an output where MR=MC as long as P>AVC. This is at an output of Q=4 so a price of P=6. Q MR 16

17. MATH BEHIND: Maximizing Profits being where MR=MC Max Q Profits = Max Q TR(Q)-TC(Q) so profits are maximized where Or where, Applies when Q>0 17

18. Monopoly Maximizing Profits At Q=4 and P=6, what is Total Revenue? TR=P*Q=6*4=24 At Q=4, what are Total Costs? TC=ATC*Q=4.5*4=18 At Q=4 and P=6, what are Profits? Profits=TR-TC=24-18=6 Or Profits=P*Q-ATC*Q =(P-ATC)*Q =(6-4.5)*4=6 Q MR TR TC Profits 18

19. Monopoly Maximizing Profits What is the difference between these costs and the costs on the prior slide? FC are greater on the costs depicted to the right. If the monopolist maximizes profits, where would it produce? Q=4 so set P=6. Profits would be: TR-TC=6*4-8*4= -8 MR Profits 19

20. Monopolist in Long Run What should this monopolist do in the Long Run assuming that the monopolist thinks his costs will not change and neither will demand? Keep producing Q=4 or change plant size depending if there is a plant size that would result in greater profits. Q MR Profits 20

21. Short Run and Long Run ATCs 21

22. Monopolist in Long Run What should this monopolist do in the Long Run assuming that the monopolist thinks his costs will not change and neither will demand? Exit the industry or change plant size depending if there is a plant size that would result in positive profits given demand curve. MR Profits 22

23. Monopolistic Competition Characteristics 1. There are many buyers and seller 2. Each firm in the industry produces a differentiated product 3. There is free entry into and exit from the industry [Think bakery or coffee shop in big city.] 23

24. Bakery in a Monopolistically Competitive Industry Maximizing Profits in the Short Run If bakery maximizes profits, where would it produce? Where MR=MC which is at an output of Q=3.5 so a price of P=8. What are the bakery’s profits? TR-TC=P*Q-ATC*Q =8*3.5 - 6.25*3.5 = 6.12 MR 24

25. Bakery in a Monopolistically Competitive Industry Maximizing Profits in the Long Run In long-run if the bakery is making positive economic profits, we would expect other bakeries to enter causing a reduction in demand. What are maximum profits when demand is D’? Q=3 so a price of P=6.67. Profits=P*Q-ATC*Q =6.67*3-6.67*3=0 MR D’ 25

26. Review of Profit Maximization (when setting a single price) 26

27. Marginal Revenue from 5 th Unit is just the shaded area below. This area is $11. MR When the MR curve is linear, the area under the MR curve can be obtained by just taking the MR at the midpoint of the quantities – in this case at 4.5. The orange area is the same as the purple area. 27

28. Marginal Cost of 5 th Unit is just the shaded area below. This area is $9. MR The purple area is the same as the red area When the MC curve is linear, the area under the MC curve can be obtained by taking the MC at the midpoint of the quantities – in this case at 4.5. 28

29. Change in Profits associated with producing 5 Units rather than 4 units. MR Yellow area is change in profits associated with producing 5 units rather than 4 units. This area is $2. Subtract MC of 5th unit from MR of 5th unit– brown area from purple. 29

30. Review of Profit Maximization (when setting a single price) 30

31. PROFIT MAXIMIZATION MR 11.2 15 Profits are maximized at an output where MR=MC which is Q=5. Price is 15 and ATC is 11.2 at Q=5. Profits are then 15*5-11.2*5=19 31