BAB 10
Persaingan sempurna
Perfect competition
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Pasar Persaingan Sempurna
 many
buyers and sellers,
 identical (also known as
homogeneous) products,
 no barriers to either entry or exit, and
 buyers and sellers have perfect
information.
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Profit maximization assumption
Firms act to maximize profit ( ).
Profit = total revenue – total cost
= PQ – FC – VC
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Profit maximization example
Q
TR
TC
 MR MC 

0
1
0
6
3
5
(3) 6
1
6
2
3
4
5
6
7
8
2
4
12 8
4
6
3
3
18 12 6
6
4
2
24 17 7
6
5
1
30 23 7
6
6
0
36 30 6
6
7
(1)
42 38 4
6
8
(2)
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
48 47 1
6
9
(3)
Rule for profit maximization
If MC is rising, produce
up to the point at which
MC = MR.
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Figure 1 Profit Maximization for a Competitive Firm
Costs
and
Revenue
The firm maximizes
profit by producing
the quantity at which
marginal cost equals
marginal revenue.
MC
MC2
ATC
P = MR1 = MR2
P = AR = MR
AVC
MC1
0
Q1
QMAX
Q2
Quantity
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 2 Marginal Cost as the Competitive Firm’s
Supply Curve
Price
P2
This section of the
firm’s MC curve is
also the firm’s supply
curve.
MC
ATC
P1
AVC
0
Q1
Q2
Quantity
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 3 The Competitive Firm’s Short Run Supply
Curve
Costs
If P > ATC, the firm
will continue to
produce at a profit.
Firm’s short-run
supply curve
MC
ATC
If P > AVC, firm will
continue to produce
in the short run.
AVC
Firm
shuts
down if
P < AVC
Quantity
0
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Shutdown vs. Exit
A shutdown refers to a short-run
decision not to produce anything
during a specific period of time.
Exit refers to a long-run decision to
leave the market.
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Figure 4 The Competitive Firm’s Long-Run Supply
Curve
Costs
Firm’s long-run
supply curve
MC = long-run S
Firm
enters if
P > ATC
ATC
Firm
exits if
P < ATC
0
Quantity
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 5 Profit as the Area between Price and Average
Total Cost
(a) A Firm with Profits
Price
MC
ATC
Profit
P
ATC
P = AR = MR
0
Quantity
Q
(profit-maximizing
quantity)
nuhfil hanani : web site
: www.nuhfil.com, email
: nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 5 Profit as the Area between Price and Average
Total Cost
(b) A Firm with Losses
Price
MC
ATC
ATC
P
P = AR = MR
Loss
0
Quantity
Q
quantity)
nuhfil hanani(loss-minimizing
: web site : www.nuhfil.com,
email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 6 Market Supply with a Fixed Number of Firms
(a) Individual Firm Supply
(b) Market Supply
Price
Price
MC
Supply
$2.00
$2.00
1.00
1.00
0
100
200
Quantity (firm)
0
100,000
200,000 Quantity (market)
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 7 Market Supply with Entry and Exit
(a) Firm’s Zero-Profit Condition
(b) Market Supply
Price
Price
MC
ATC
P = minimum
ATC
0
Supply
Quantity (firm)
Quantity (market)
0
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 8 An Increase in Demand in the Short Run and
Long Run
(a) Initial Condition
Market
Firm
Price
Price
MC
ATC
Short-run supply, S1
A
P1
Long-run
supply
P1
Demand, D1
0
Quantity (firm)
0
Q1
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Quantity (market)
Figure 8 An Increase in Demand in the Short Run and
Long Run
(b) Short-Run Response
Market
Firm
Price
Price
Profit
MC
ATC
P2
B
P2
S1
A
P1
P1
D2
Long-run
supply
D1
0
Quantity (firm)
0
Q1
Q2
Quantity (market)
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western
Figure 8 An Increase in Demand in the Short Run and
Long Run
(c) Long-Run Response
Market
Firm
Price
Price
MC
ATC
B
P2
S1
S2
C
A
P1
Long-run
supply
P1
D2
D1
0
Quantity (firm)
0
Q1
Q2
Q3 Quantity (market)
nuhfil hanani : web site : www.nuhfil.com, email : nuhfil@yahoo.com
Copyright © 2004 South-Western