1. Managerial Decisions in Competitive Markets
Chapter 11
Managerial Decisions in Competitive Markets

2. Perfect Competition Firms are price-takers
Each produces only a very small amount of total market or industry output
All firms produce a homogeneous (identical) product
Entry into & exit from the market is unrestricted (can easily enter market)

3. Demand for a Competitive Price-Taker
Demand curve is horizontal at price determined by intersection of market demand & supply
Perfectly elastic
Marginal revenue equals price
Demand curve is also marginal revenue curve (D = MR)
Can sell all they want at the market price
Each additional unit of sales adds to total revenue an amount equal to price

4. Demand for a Competitive Price-Taking Firm (Figure 11.2)S
Price (dollars) D
Price (dollars) P0 P0
D = MR Q0
Quantity
Quantity
Panel A – Market
Panel B – Demand curve facing a price-taker

5. Profit-Maximization in the Short Run
In the short run, managers must make two decisions:
Produce or shut down?
If shut down, produce no output and hires no variable inputs
If shut down, firm loses amount equal to TFC
If produce, what is the optimal output level?
If firm does produce, then how much?
Produce amount that maximizes economic profit
Profit =

6. Profit Margin (or Average Profit)
Level of output that maximizes total profit occurs at a higher level than the output that maximizes profit margin (& average profit)
Managers should ignore profit margin (average profit) when making optimal decisions

7. Short-Run Output Decision
Firm’s manager will produce output where P = MC as long as:
TR  TVC
or, equivalently, P  AVC
If price is less than average variable cost (P  AVC), manager will shut down
Produce zero output
Lose only total fixed costs
Shutdown price is minimum AVC

8. Profit Maximization: P = $36 (Figure 11.3)
Total revenue =$36 x = $21,600
Total cost = $19 x = $11,400

9. Profit Maximization: P = $36 (Figure 11.4)
Panel A: Total revenue & total cost
Panel B: Profit curve when P = $36

10. Short-Run Loss Minimization: P = $10.50 (Figure 11.5)
Total cost = $17 x = $5,100
Profit = $3,150 - $5, = -$1,950
Total revenue = $10.50 x = $3,150

11. Irrelevance of Fixed Costs
Fixed costs are irrelevant in the production decision
Level of fixed cost has no effect on marginal cost or minimum average variable cost
Thus no effect on optimal level of output

12. Summary of Short-Run Output Decision
AVC tells whether to produce
Shut down if price falls below minimum AVC
SMC tells how much to produce
If P  minimum AVC, produce output at which P = SMC
ATC tells how much profit/loss if produce •

13. Short-Run Supply Curves
For an individual price-taking firm
Portion of firms’ marginal cost curve above minimum AVC
For prices below minimum AVC, quantity supplied is zero
For a competitive industry
Horizontal sum of supply curves of all individual firms
Always upward sloping

14. Derivation of Short-Run Supply Curves (Figure 11.6)

15. Long-Run Profit-Maximizing Equilibrium (Figure 11.7)
Profit = ($17 - $12) x 240 = $1,200

16. Long-Run Competitive Equilibrium
All firms are in profit-maximizing equilibrium (P = LMC)
Occurs because of entry/exit of firms in/out of industry
Market adjusts so P = LMC = LAC

17. Long-Run Competitive Equilibrium (Figure 11.8)

18. Long-Run Industry Supply
Long-run industry supply curve can be flat (perfectly elastic) or upward sloping
Depends on whether constant cost industry or increasing cost industry
Economic profit is zero for all points on the long-run industry supply curve for both types of industries

19. Long-Run Industry Supply
Constant cost industry
As industry output expands, input prices remain constant, & minimum LAC is unchanged
P = minimum LAC, so curve is horizontal (perfectly elastic)
Increasing cost industry
As industry output expands, input prices rise, & minimum LAC rises
Long-run supply price rises & curve is upward sloping

20. Long-Run Industry Supply for a Constant Cost Industry (Figure 11.9)

21. Long-Run Industry Supply for an Increasing Cost Industry (Figure 11
Firm’s output

22. Economic Rent
Payment to the owner of a scarce, superior resource in excess of the resource’s opportunity cost
In long-run competitive equilibrium firms that employ such resources earn only normal profit
Economic profit is zero
Potential economic profit is paid to the resource as rent

23. Economic Rent in Long-Run Competitive Equilibrium (Figure 11.11)

24. Implementing the Profit-Maximizing Output Decision
Step 1: Forecast product price
Use statistical techniques from Chapter 7
Step 2: Estimate AVC & SMC • •

25. Implementing the Profit-Maximizing Output Decision
Step 3: Check shutdown rule
If P  AVCmin, produce
If P < AVCmin, shut down
To find AVCmin, substitute Qmin into AVC equation

26. Implementing the Profit-Maximizing Output Decision
Step 4: If P  AVCmin, find output where P = SMC
Set forecasted price equal to estimated marginal cost & solve for Q*

27. Implementing the Profit-Maximizing Output Decision
Step 5: Compute profit or loss
Profit = TR - TC
If P < AVCmin, firm shuts down & profit is -TFC

28. Profit & Loss at Beau Apparel (Figure 11.13)

29. Profit & Loss at Beau Apparel (Figure 11.13)

30. Homework Read Chapter 11 pages 396 – 421
Do Tech probs. 1, 2, 3, 4, 6, 7, 8, 9
Do Applied problems: 1, 6, 7, 8