Transcript PPT_Mic9e_one_click_ch08

CHAPTER 8 Short-Run Costs and Output Decisions
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© 2009 Pearson Education, Inc. Publishing as Prentice Hall
Principles of
Microeconomics, 9e
; ;
By
Karl E. Case,
Ray C. Fair &
Sharon M. Oster
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CHAPTER 8 Short-Run Costs and Output Decisions
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PART II THE MARKET SYSTEM
Choices Made by Households and Firms
8
Short-Run Costs and
Output Decisions
Prepared by:
Fernando & Yvonn Quijano
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Principles of Microeconomics 9e by Case, Fair and Oster
PART II THE MARKET SYSTEM
Choices Made by Households and Firms
8
CHAPTER 8 Short-Run Costs and Output Decisions
Short-Run Costs and
Output Decisions
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CHAPTER OUTLINE
Costs in the Short Run
Fixed Costs
Variable Costs
Total Costs
Short-Run Costs: A Review
Output Decisions: Revenues,
Costs, and Profit Maximization
Total Revenue (TR) and Marginal
Revenue (MR)
Comparing Costs and Revenues to
Maximize Profit
The Short-Run Supply Curve
Looking Ahead
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Short-Run Costs and Output Decisions
CHAPTER 8 Short-Run Costs and Output Decisions
You have seen that firms in perfectly competitive
industries make three specific decisions.
 FIGURE 8.1 Decisions Facing Firms
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CHAPTER 8 Short-Run Costs and Output Decisions
Costs in the Short Run
fixed cost Any cost that does not depend on the
firms level of output. These costs are incurred even
if the firm is producing nothing. There are no fixed
costs in the long run.
variable cost A cost that depends on the level of
production chosen.
total cost (TC) Fixed costs plus variable costs.
TC = TFC + TVC
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Costs in the Short Run
Fixed Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Total Fixed Cost (TFC)
total fixed costs (TFC) or overhead The total of
all costs that do not change with output even if
output is zero.
TABLE 8.1 Short-Run Fixed Cost (Total and
Average) of a Hypothetical Firm
(1) Q
(2) TFC
0
1
2
3
4
5
$1,000
1,000
1,000
1,000
1,000
1,000
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(3) AFC (TFC/Q)
$
1,000
500
333
250
200
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Costs in the Short Run
Fixed Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Total Fixed Cost (TFC)
 FIGURE 8.2 Short-Run Fixed Cost (Total and Average) of a Hypothetical Firm
Average fixed cost is simply total fixed cost divided by the quantity of output. As output
increases, average fixed cost declines because we are dividing a fixed number ($1,000) by a
larger and larger quantity.
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Costs in the Short Run
Fixed Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Average Fixed Cost (AFC)
average fixed cost (AFC) Total fixed cost divided
by the number of units of output; a per-unit
measure of fixed costs.
TFC
AFC 
q
spreading overhead The process of dividing
total fixed costs by more units of output. Average
fixed cost declines as quantity rises.
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Total Variable Cost (TVC)
total variable cost (TVC) The total of all costs
that vary with output in the short run.
total variable cost curve A graph that shows the
relationship between total variable cost and the
level of a firm’s output.
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Costs in the Short Run
Variable Costs
Total Variable Cost (TVC)
CHAPTER 8 Short-Run Costs and Output Decisions
TABLE 8.2 Derivation of Total Variable Cost Schedule from Technology and Factor Prices
Produce
1 unit of
output
2 units of
output
3 units of
output
Using
Technique
Units of Input Required
(Production Function)
K
L
Total Variable Cost Assuming
PK = $2, PL = $1
TVC = (K x PK) + (L x PL)
A
4
4
(4 x $2) + (4 x $1)
= $12
B
2
6
(2 x $2) + (6 x $1)
= $10
A
7
6
(7 x $2) + (6 x $1)
= $20
B
4
10
A
9
6
B
6
14
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(4 x $2) + (10 x $1) = $18
(9 x $2) + (6 x $1)
= $24
(6 x $2) + (14 x $1) = $26
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Total Variable Cost (TVC)
 FIGURE 8.3 Total Variable
Cost Curve
In Table 8.2, total variable cost is
derived from production requirements
and input prices. A total variable cost
curve expresses the relationship
between TVC and total output.
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Marginal Cost (MC)
marginal cost (MC) The increase in total cost that
results from producing 1+ more unit of output.
Marginal costs reflect changes in variable costs.
TABLE 8.3 Derivation of Marginal Cost from Total Variable Cost
Units of Output
Total Variable Costs ($)
0
1
2
3
0
10
18
24
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Marginal Costs ($)
10
8
6
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
The Shape of the Marginal Cost Curve in the Short Run
 FIGURE 8.4 Declining Marginal Product Implies
That Marginal Cost Will Eventually Rise with Output
In the short run, every firm is constrained by some fixed factor of production. A fixed factor implies
diminishing returns (declining marginal product) and a limited capacity to produce.
As that limit is approached, marginal costs rise.
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
The Shape of the Marginal Cost Curve in the Short Run
In the short run, every firm is constrained by some
fixed input that (1) leads to diminishing returns to
variable inputs and (2) limits its capacity to
produce. As a firm approaches that capacity, it
becomes increasingly costly to produce
successively higher levels of output. Marginal
costs ultimately increase with output in the short
run.
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Graphing Total Variable Costs
and Marginal Costs
 FIGURE 8.5 Total Variable Cost and
Marginal Cost for a Typical Firm
Total variable costs always increase
with output. Marginal cost is the cost
of producing each additional unit.
Thus, the marginal cost curve shows
how total variable cost changes with
single- unit increases in total output.
slope of TVC 
TVC TVC

 TVC  MC
Δq
1
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Average Variable Cost (AVC)
average variable cost (AVC) Total variable cost
divided by the number of units of output.
TVC
AVC 
q
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Costs in the Short Run
Variable Costs
Average Variable Cost (AVC)
CHAPTER 8 Short-Run Costs and Output Decisions
TABLE 8.4 Short-Run Costs of a Hypothetical Firm
(1)
q
(2)
TVC
(3)
MC
( TVC)
(4)
AVC
(TVC/q)
(5)
TFC
(6)
TC
(TVC + TFC)
-
$1,000
$ 1,000
(7)
AFC
(TFC/q)
0
$ -
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
0
$
$
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9,000
$
-
(8)
ATC (TC/q or
AFC + AVC)
-
$
2
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Costs in the Short Run
Variable Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Graphing Average Variable Costs and Marginal Costs
 FIGURE 8.6 More Short-Run
Costs
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 cost at the
minimum point of AVC.
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Costs in the Short Run
CHAPTER 8 Short-Run Costs and Output Decisions
Total Costs
 FIGURE 8.7 Total Cost = Total Fixed Cost + Total Variable Cost
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.
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Costs in the Short Run
Total Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Average Total Cost (ATC)
average total cost (ATC) Total cost divided by
the number of units of output.
TC
ATC 
q
ATC  AFC  AVC
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Costs in the Short Run
Total Costs
CHAPTER 8 Short-Run Costs and Output Decisions
Average Total Cost (ATC)
 FIGURE 8.8 Average Total Cost =
Average Variable Cost + Average
Fixed Cost
To get average total cost, we add
average fixed and average variable
costs at all levels of output.
Because average fixed cost falls
with output, an ever-declining
amount is added to AVC.
Thus, AVC and ATC get closer
together as output increases, but
the two lines never meet.
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Costs in the Short Run
Total Costs
CHAPTER 8 Short-Run Costs and Output Decisions
The Relationship Between Average Total Cost and Marginal Cost
The relationship between average total cost and
marginal cost is exactly the same as the
relationship between average variable 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. As a result,
marginal cost intersects average total cost at
ATC’s minimum point, for the same reason that it
intersects the average variable cost curve at its
minimum point.
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Costs in the Short Run
Short-Run Costs: A Review
TABLE 8.5 A Summary of Cost Concepts
CHAPTER 8 Short-Run Costs and Output Decisions
Term
Definition
Equation
Accounting costs
Out-of-pocket costs or costs as an accountant would
define them. Sometimes referred to as explicit costs.
-
Economic costs
Costs that include the full opportunity costs of all
inputs. These include what are often called implicit
costs.
-
Total fixed costs
Costs that do not depend on the quantity of output
produced. These must be paid even if output is zero.
TFC
Total variable costs
Costs that vary with the level of output.
TVC
Total cost
The total economic cost of all the inputs
used by a firm in production.
Average fixed costs
Fixed costs per unit of output.
Average variable costs Variable costs per unit of output.
Average total costs
Total costs per unit of output.
Marginal costs
The increase in total cost that results from
producing 1 additional unit of output.
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TC = TFC + TVC
AFC = TFC/q
AVC = TVC/q
ATC = TC/q ATC = AFC + AVC
MC = TC/q
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Costs in the Short Run
Short-Run Costs: A Review
CHAPTER 8 Short-Run Costs and Output Decisions
Average and Marginal Costs at a College
Students
Costs in Dollars
Total Fixed Cost Total Variable Cost Total Cost
Average Total Cost
500
$60 million
$ 20 million
$ 80 million
$160,000
1,000
60 million
40 million
100 million
100,000
1,500
60 million
60 million
120 million
80.000
2,000
60 million
80 million
140 million
70,000
2,500
60 million
100 million
60 million
60,000
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Output Decisions: Revenues, Costs, and Profit Maximization
CHAPTER 8 Short-Run Costs and Output Decisions
Perfect Competition
perfect competition An industry structure in
which there are many firms, each small relative to
the industry, producing virtually identical products
and in which no firm is large enough to have any
control over prices. In perfectly competitive
industries, new competitors can freely enter and
exit the market.
homogeneous products Undifferentiated
products; products that are identical to, or
indistinguishable from, one another.
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Output Decisions: Revenues, Costs, and Profit Maximization
CHAPTER 8 Short-Run Costs and Output Decisions
Perfect Competition
 FIGURE 8.9 Demand Facing a Single
Firm In a Perfectly Competitive Market
If a representative firm in a perfectly competitive market raises the price of its output
above $2.45, the quantity demanded of that firm’s output will drop to zero. Each firm
faces a perfectly elastic demand curve, d.
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Output Decisions: Revenues, Costs, and Profit Maximization
CHAPTER 8 Short-Run Costs and Output Decisions
Total Revenue (TR) and Marginal Revenue (MR)
total revenue (TR) The total amount that a firm
takes in from the sale of its product: the price per
unit times the quantity of output the firm decides to
produce (P x q).
total revenue  price x quantity
TR  P x q
marginal revenue (MR) The additional revenue
that a firm takes in when it increases output by one
additional unit. In perfect competition, P = MR.
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Output Decisions: Revenues, Costs, and Profit Maximization
Comparing Costs and Revenues to Maximize Profit
CHAPTER 8 Short-Run Costs and Output Decisions
The Profit-Maximizing Level of Output
 FIGURE 8.10 The Profit-Maximizing Level of Output for a Perfectly Competitive Firm
If price is above marginal cost, as it is at 100 and 250 units of output, profits can be increased by
raising output; each additional unit increases revenues by more than it costs to produce the
additional output. Beyond q* = 300, however, added output will reduce profits. At 340 units of output,
an additional unit of output costs more to produce than it will bring in revenue when sold on the
market. Profit-maximizing output is thus q*, the point at which P* = MC.
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Output Decisions: Revenues, Costs, and Profit Maximization
Comparing Costs and Revenues to Maximize Profit
CHAPTER 8 Short-Run Costs and Output Decisions
The Profit-Maximizing Level of Output
As long as marginal revenue is greater than
marginal cost, even though the difference between
the two is getting smaller, added output means
added profit. Whenever marginal revenue
exceeds marginal cost, the revenue gained by
increasing output by 1 unit per period exceeds the
cost incurred by doing so.
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
level of output at which P* = MC.
The profit-maximizing output level for all firms is
the output level where MR = MC.
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Output Decisions: Revenues, Costs, and Profit Maximization
Comparing Costs and Revenues to Maximize Profit
A Numerical Example
CHAPTER 8 Short-Run Costs and Output Decisions
TABLE 8.6 Profit Analysis for a Simple Firm
(1)
(2)
(3)
(4)
(5)
q
TFC
TVC
MC
P = MR
(6)
TR
(P x q)
$
$
$
0
$
-
0
$
(8)
PROFIT
(TR - TC)
0
$ 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
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15
(7)
TC
(TFC + TVC)
10
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$
-10
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Output Decisions: Revenues, Costs, and Profit Maximization
Comparing Costs and Revenues to Maximize Profit
CHAPTER 8 Short-Run Costs and Output Decisions
A Numerical Example
Case Study in Marginal
Analysis: An Ice Cream
Parlor
An analysis of fixed costs,
variable costs, revenues, profits,
and opening longer hours were
used by this ice cream parlor to
determine whether to stay in
business.
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Output Decisions: Revenues, Costs, and Profit Maximization
CHAPTER 8 Short-Run Costs and Output Decisions
The Short-Run Supply Curve
 FIGURE 8.11 Marginal Cost Is the Supply Curve of a Perfectly Competitive Firm
At any market price,a 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.
a
This is true except when price is so low that it pays a firm to shut down—a point that will be discussed in
Chapter 9.
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CHAPTER 8 Short-Run Costs and Output Decisions
REVIEW TERMS AND CONCEPTS
average fixed cost (AFC)
total variable cost (TVC)
average total cost (ATC)
total variable cost curve
average variable cost (AVC)
variable cost
fixed cost
1. TC = TFC + TVC
homogeneous product
2. AFC = TFC/q
marginal cost (MC)
3. Slope of TVC = MC
marginal revenue (MR)
4. AVC = TVC/q
perfect competition
5. ATC = TC/q = AFC + AVC
spreading overhead
6. TR = P x q
total cost (TC)
7. Profit-maximizing level of output for
all firms: MR = MC
total fixed costs (TFC) or
overhead
total revenue (TR)
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8. Profit-maximizing level of output for
perfectly competitive firms: P = MC
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