princ-ch14-presentation6e mankiw_6版微观经济学部分12-22章完整PPT(全英文)

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MR = P for a Competitive Firm
A competitive firm can keep increasing its output without affecting the market price. So, each one-unit increase in Q causes revenue to rise by P, i.e., MR = P. MR = P is only true for firms in competitive markets.
N. Gregory Mankiw
Economics
Principles of
Sixth Edition
14
Firms in Competitive Markets
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Profit =
MR – MC $6 4 2 0 –2
6 8 10 12
4 5Leabharlann 40 5033 45
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3
The Revenue of a Competitive Firm
Total revenue (TR)
Average revenue (AR) TR = P x Q
TR =P AR = Q ∆TR MR = ∆Q
Marginal revenue (MR): The change in TR from selling one more unit.
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7
Profit Maximization
What Q maximizes the firm’s profit?
To find the answer, ―think at the margin.‖
If increase Q by one unit, revenue rises by MR, cost rises by MC. If MR > MC, then increase Q to raise profit.
total and average revenue?
• How does a competitive firm determine the
quantity that maximizes profits?
• When might a competitive firm shut down in the
short run? Exit the market in the long run?
What factors should affect these decisions? Your costs (studied in preceding chapter) How much competition you face
We begin by studying the behavior of firms in perfectly competitive markets.
ACTIVE LEARNING
Answers
Q 0 1 2 P $10 $10 $10
1
AR = TR Q MR = ∆TR
Fill in the empty spaces of the table.
TR = P x Q $0 $10
∆Q
n/a $10 $10
Notice that $20 $10 MR = P
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ACTIVE LEARNING
Calculating TR, AR, MR
Fill in the empty spaces of the table.
Q 0 1 2 P $10 $10 $10 TR AR n/a $10 MR
1
3
4 5
$10
$10 $10 $40 $10 $50
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$30
$40 $50
$10
$10 $10
3
4 5
$10
$10 $10
$10
$10 $10 $10
© 2012 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
© 2012 Cengage Learning. All Rights ReMay served. not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
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Introduction: A Scenario
Three years after graduating, you run your own business. You must decide how much to produce, what price to charge, how many workers to hire, etc.
If MR < MC, then reduce Q to raise profit.
© 2012 Cengage Learning. All Rights ReMay served. not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use.
8
Profit Maximization
(continued from earlier exercise)
Q 0 1 2 3 TR $0 10 20 30 TC $5 9 15 23 Profit MR MC –$5 $10 $4 1 10 5 10 7 10 7 10 5
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At any Q with MR > MC, increasing Q raises profit. At any Q with MR < MC, reducing Q raises profit.
Because of 1 & 2, each buyer and seller is a