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# Ch07

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### Ch07

1. 1. Decisions Facing Firms DECISIONS are based on INFORMATION 1. The quantity of output to 1. The price of output supply 2. How to produce that 2. Techniques of output (which technique production available* to use) 3. The quantity of each 3. The price of inputs* input to demand *Determines production costs© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
2. 2. Costs in the Short Run • The short run is a period of time for which two conditions hold: 1. The firm is operating under a fixed scale (fixed factor) of production, and 2. Firms can neither enter nor exit an industry. • In the short run, all firms have costs that they must bear regardless of their output. These kinds of costs are called fixed costs.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
3. 3. Costs in the Short Run • Fixed cost is any cost that does not depend on the firm’s level of output. These costs are incurred even if the firm is producing nothing. • Variable cost is a cost that depends on the level of production chosen. TC = TFC + TVC Total Cost = Total Fixed + Total Variable Cost Cost© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
4. 4. Fixed Costs • Firms have no control over fixed costs in the short run. For this reason, fixed costs are sometimes called sunk costs. • Average fixed cost (AFC) is the total fixed cost (TFC) divided by the number of units of output (q): TFC AFC = q© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
5. 5. Short-Run Fixed Cost (Total and Average) of a Hypothetical Firm (1) (2) (3) q TFC AFC (TFC/q) 0 \$1,000 \$ −− 1 1,000 1,000 2 1,000 500 3 1,000 333 4 1,000 250 5 1,000 200 • AFC falls as output rises; a phenomenon sometimes called spreading overhead.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
6. 6. Variable Costs • The total variable cost curve is a graph that shows the relationship between total variable cost and the level of a firm’s output. • The total variable cost is derived from production requirements and input prices.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
7. 7. Derivation of Total Variable Cost Schedule from Technology and Factor Prices UNITS OF INPUT REQUIRED (PRODUCTION FUNCTION) TOTAL VARIABLE COST ASSUMING USING PK = \$2, PL = \$1 PRODUCT TECHNIQUE K L TVC = (K x PK) + (L x PL) \$10 1 Units of A 4 4 (4 x \$2) + (4 x \$1) = \$12 output B 2 6 (2 x \$2) + (6 x \$1) = \$18 2 Units of A 7 6 (7 x \$2) + (6 x \$1) = \$20 \$24 output B 4 10 (4 x \$2) + (10 x \$1) = 3 Units of A 9 6 (9 x \$2) + (6 x \$1) = • The output B 6 curve14 shows the\$2) + (14 x \$1) = \$26 The total variable cost curve shows the cost of variable cost (6 x cost of production using the best available technique at each output level, given current factor prices.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
8. 8. Marginal Cost • Marginal cost (MC) is the increase in total cost that results from producing one more unit of output. • Marginal cost reflects changes in variable costs. ∆TC ∆TFC ∆TVC M C = = + ∆Q ∆Q ∆Q© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
9. 9. Derivation of Marginal Cost from Total Variable Cost TOTAL VARIABLE COSTS MARGINAL COSTS UNITS OF OUTPUT (\$) (\$) 0 0 0 1 10 10 2 18 8 3 24 6 • Marginal cost measures the additional cost of inputs required to produce each successive unit of output.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
10. 10. The Shape of the Marginal Cost Curve in the Short Run • The fact that in the short run every firm is constrained by some fixed input means that: 1. The firm faces diminishing returns to variable inputs, and 2. The firm has limited capacity to produce output. • As a firm approaches that capacity, it becomes increasingly costly to produce successively higher levels of output.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
11. 11. The Shape of the Marginal Cost Curve in the Short Run • Marginal costs ultimately increase with output in the short run.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
12. 12. Graphing Total Variable Costs and Marginal Costs • Total variable costs always increase with output. The marginal cost curve shows how total variable cost changes with single unit increases in total output. • Below 100 units of output, TVC increases at a decreasing rate. Beyond 100 units of output, TVC increases at an increasing rate.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
13. 13. Average Variable Cost • Average variable cost (AVC) is the total variable cost divided by the number of units of output. • Marginal cost is the cost of one additional unit. Average variable cost is the average variable cost per unit of all the units being produced. • Average variable cost follows marginal cost, but lags behind.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
14. 14. Relationship Between Average Variable Cost and Marginal Cost • When marginal cost is below average cost, average cost is declining. • When marginal cost is above average cost, average cost is increasing. • Rising marginal cost intersects average variable • At 200 units of output, AVC is cost at the minimum point minimum, and MC = AVC. of AVC.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
15. 15. Short-Run Costs of a Hypothetical Firm (3) (4) (6) (7) (8) (1) (2) MC AVC (5) TC AFC ATC q TVC (∆ TVC) (TVC/q) TFC (TVC + TFC) (TFC/q) (TC/q or AFC + AVC) 0 \$ 0 \$ − \$ − \$ 1,000 \$ 1,000 \$ − \$ − 1 10 10 10 1,000 1,010 1,000 1,010 2 18 8 9 1,000 1,018 500 509 3 24 6 8 1,000 1,024 333 341 4 32 8 8 1,000 1,032 250 258 5 42 10 8.4 1,000 1,042 200 208.4 − − − − − − − − − − − − − − − − − − − − − − − − 500 8,000 20 16 1,000 9,000 2 18© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
16. 16. Total Costs • Adding TFC to TVC means adding the same amount of total fixed cost to every level of total variable cost. • Thus, the total cost curve has the same shape as the total variable cost curve; it is simply higher by an amount equal to TFC. TC = TFC + TVC© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
17. 17. Average Total Cost • Average total cost (ATC) is total cost divided by the number of units of output (q). ATC = AFC + AVC TC TFC TVC ATC = = + q q q • Because AFC falls with output, an ever-declining amount is added to AVC.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
18. 18. Relationship Between Average Total Cost and Marginal Cost • If marginal cost is below average total cost, average total cost will decline toward marginal cost. • If marginal cost is above average total cost, average total cost will increase. • Marginal cost intersects average total cost and average variable cost curves at their minimum points.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
19. 19. Output Decisions: Revenues, Costs, and Profit Maximization • In the short run, a competitive firm faces a demand curve that is simply a horizontal line at the market equilibrium price.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
20. 20. Total Revenue (TR) and Marginal Revenue (MR) • Total revenue (TR) is the total amount that a firm takes in from the sale of its output. TR = P × q • Marginal revenue (MR) is the additional revenue that a firm takes in when it increases output by one additional unit. • In perfect competition, P = MR. ∆TR P (∆q ) M R = = = P ∆q ∆q© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
21. 21. Comparing Costs and Revenues to Maximize Profit • The profit-maximizing level of output for all firms is the output level where MR = MC. • In perfect competition, MR = P, therefore, the profit-maximizing perfectly competitive firm will produce up to the point where the price of its output is just equal to short-run marginal cost. • The key idea here is that firms will produce as long as marginal revenue exceeds marginal cost.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
22. 22. Profit Analysis for a Simple Firm (6) (7) (8) (1) (2) (3) (4) (5) TR TC PROFIT q TFC TVC MC P = MR (P x q) (TFC + TVC) (TR − TC) 0 \$ 10 \$ 0 \$ − \$ 15 \$ 0 \$ 10 \$ -10 1 10 10 10 15 15 20 -5 2 10 15 5 15 30 25 5 3 10 20 5 15 45 30 15 4 10 30 10 15 60 40 20 5 10 50 20 15 75 60 15 6 10 80 30 15 90 90 0© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
23. 23. The Short-Run Supply Curve • At any market price, the marginal cost curve shows the output level that maximizes profit. Thus, the marginal cost curve of a perfectly competitive profit-maximizing firm is the firm’s short-run supply curve.© 2002 Prentice Hall Business Publishing Principles of Economics, 6/e Karl Case, Ray Fair
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