Perfect Competition

1

Review1. Identify the 4 Market Structures2. Identify the characteristics of perfect competition3. Why is a perfectly competitive firm a “price

taker”?4. Explain why perfectly competitive firms make

little profit5. How do ALL firms determine what output to

produce?6. Draw a perfectly competitive firm producing 10

units at a price of $10 making a profit of $307. Draw and label a perfectly competitive firm

making a loss. 8. On your graph, identify the shut down point9. List 10 words that rhyme with the word “great”

2

P

Q

P

Q5000

D

S

Industry Firm(price taker)

$15 $15

Side-by-side graph for perfectly completive industry and firm.

3

AVCMR=D

ATC

MC

8

Is the firm making a profit or a loss? Why?

Total Revenue

$25

20

15

10

0

Co

st a

nd

Rev

enu

e

1 2 3 4 5 6 7 8 9 10

MC

AVC

ATC

Where is the profit maximization point? How do you know?

MR=P

Total Cost

Profit

How much is the profit or loss?

What is TR? What is TC?

Where is the Shutdown Point?

What output should be produced?

4

Supply Revisited

5

$50

4540353025 2015 10

5 0

Cos

t an

d R

even

ue

1 2 3 4 5 6 7 9

AVC

ATC

6

MR1

Marginal Cost and Supply

MR2

MR3

MR4

MR5

MC

Q

As price increases, the quantity increases

When price increases, quantity increases When price decrease, quantity decreases

$50

4540353025 2015 10

5 0

Cos

t an

d R

even

ue

1 2 3 4 5 6 7 9

AVC

ATC

7

Marginal Cost and Supply

MC

Q

= Supply

MC above AVC is the supply curve

What if variable costs increase (ex: tax)?

$50

4540353025 2015 10

5 0

Cos

t an

d R

even

ue

1 2 3 4 5 6 7 9

AVC

8

Marginal Cost and Supply

Q

MC1=Supply1

AVC

MC2=Supply2

When MC increases, SUPPLY decrease

What if variable costs decrease (ex: subsidy)?

$50

4540353025 2015 10

5 0

Cos

t an

d R

even

ue

1 2 3 4 5 6 7 9

AVC

9

Marginal Cost and Supply

Q

MC1=Supply1

AVC

MC2=Supply2

When MC decreases, SUPPLY increases

Perfect Competition

in the Long-Run

10

You are a wheat farmer. You learn that there is a more profit in making corn.

What do you do in the long run?

In the Long-run…•Firms will enter if there is profit•Firms will leave if there is loss•So, ALL firms break even, they make NO economic profit

(No Economic Profit=Normal Profit) •In long run equilibrium a perfectly competitive firm is EXTREMELY efficient.

11

P

Q

P

Q5000

D

S

Industry Firm(price taker)

$15 $15

Side-by-side graph for perfectly completive industry and firm in the LONG RUN

12

MR=D

ATC

MC

8

Is the firm making a profit or a loss? Why?

Price = MC = Minimum ATCFirm making a normal profit

Firm in Long-Run Equilibrium

13

P

Q

$15

13

MR=D

ATC

MC

8

There is no incentive to enter or leave the

industryTC = TR

Going from Long-Run to Short-Run

14

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

15

MR=DATC

MC

8

1. Is this the short or the long run? Why?2. What will firms do in the long run?3. What happens to P and Q in the industry?4. What happens to P and Q in the firm?

6000

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

16

MR=DATC

MC

8

S1

$10

Firms enter to earn profit so supply increases in the industry

Price decreases and quantity increases

6000

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

17

MR=DATC

MC

8

Price falls for the firm because they are price takers.

Price decreases and quantity decreases

S1

$10 $10 MR1=D1

56000

P

Q

P

Q5000

D

Industry Firm 18

ATC

MC

New Long Run Equilibrium at $10 PriceZero Economic Profit

S1

$10 $10 MR1=D1

56000

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

19

MR=D

ATCMC

8

1. Is this the short or the long run? Why?2. What will firms do in the long run?3. What happens to P and Q in the industry?4. What happens to P and Q in the firm?

4000

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

20

MR=D

MC

8

S1

$20

Firms leave to avoid losses so supply decreases in the industry

Price increases and quantity decreases

ATC

4000

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

21

MR=D

MC

8

S1

$20

Price increase for the firm because they are price takers.

Price increases and quantity increases

ATC

4000

MR1=D1

9

$20

P

Q

P

Q

D

Industry Firm 22

MC

S1

$20

New Long Run Equilibrium at $20 PriceZero Economic Profit

ATC

4000

MR1=D1

9

$20

Going from Long-Run to Long-Run

23

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

24

MR=D

MC

8

Currently in Long-Run Equilibrium If demand increases, what happens in the short-run

and how does it return to the long run?

ATC

MR1=D1

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

25

MR=D

MC

8

D1

$20

Demand Increases The price increases and quantity increases

Profit is made in the short-run

ATC

MR1=D1

9

$20

P

Q

P

Q5000

D

S

Industry Firm

$15 $15

26

MR=D

MC

8

D1

$20

Firms enter to earn profit so supply increases in the industry

Price Returns to $15

ATC

MR1=D1

9

$20

7000

S1

P

Q

P

Q

D

Industry Firm

$15 $15

27

MR=D

MC

8

D1

Back to Long-Run EquilibriumThe only thing that changed from long-run to

long-run is quantity in the industry

ATC

7000

S1

Efficiency

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PURE COMPETITION AND EFFICIENCY

•Perfect Competition forces producers to use limited resources to their fullest.•Inefficient firms have higher costs and are the first to leave the industry.•Perfectly competitive industries are extremely efficient

In general, efficiency is the optimal use of societies scarce resources

1. Productive Efficiency2. Allocative Efficiency

There are two kinds of efficiency:

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Efficiency RevisitedB

ikes

Computers

14

12

10

8

6

4

2

0

0 2 4 6 8 10

A

B

C

D

F

E

Which points are productively efficient?Which are allocatively efficient?

G

30

Productive Efficient combinations are A through D

(they are produced at the lowest cost)

Allocative Efficient combinations depend on

the wants of society

Productive Efficiency

Price = Minimum ATC

The production of a good in a least costly way. (Minimum amount of resources are being used)

Graphically it is where…

31

P

Q

MCATC

Quantity

Pri

ce

Notice that the product is NOT being made at the lowest possible cost (ATC not at lowest point).

Short-Run

Profit

32

D=MR

P

Q

MC

ATC

Quantity

Pri

ce

Notice that the product is NOT being made at the lowest possible cost (ATC not at lowest point).

Short-Run

Loss

33

D=MR

PD=MR

Q

MCATC

Quantity

Pri

ce

Notice that the product is being made at the lowest possible cost (Minimum ATC)

Long-Run Equilibrium

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Allocative Efficiency

Price = MC

Producers are allocating resources to make the products most wanted by society.

Graphically it is where…

35

Why? Price represents the benefit people get from a product.

P MR

Q

MC

Quantity

Pri

ce

The marginal benefit to society (as measured by the price) equals

the marginal cost.

Long-Run Equilibrium

Optimal amount being produced

36

$5 MR

15

MC

Quantity

Pri

ce

The marginal benefit to society is greater the

marginal cost.Not enough produced.

Society wants more

What if the firm makes 15 units?

20 Underallocation of resources

$3

37

$5 MR

22

MC

Quantity

Pri

ce

The marginal benefit to society is less than the

marginal cost. Too much Produced.Society wants less

20 Overallocation of resources

$7

38

What if the firm makes 22 units?

PD=MR

Q

MCATC

Quantity

Pri

ce

P = Minimum ATC = MCEXTREMELY EFFICIENT!!!!

Long-Run Equilibrium

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