# ECON 1001 AB Introduction to Economics ID r. Ka-fu WONG

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```					      Chapter 9
Monopoly, Oligopoly, and
Monopolistic Competition
Odd-numbered Qs
Problem #1, Chapter 9

• Two car manufacturers, Saab and Volvo, have fixed costs of \$1
billion and marginal costs of \$10,000 per car. If Saab produces
50,000 cars per year and Volvo produces 200,000, calculate
the average production cost for each company. On the basis of
these costs, which company’s market share do you think will
grow in relative terms?
Solution to Problem #1 (1)

• Given in the question, both manufacturers have a fixed cost of
\$1 billion and a marginal cost of \$10,000 per car
• Marginal cost = Variable cost
• Total variable cost (TVC)= Marginal cost * quantity
• Saab
–   TVCSaab = 10,000 * 50,000 = \$500,000,000
–   Total cost (TC) = Total variable cost + Total fixed cost
–   TCSaab = \$500,000,000 + \$1,000,000,000 = \$1.5 billion
–   ACSaab= \$1.5 billion / 50,000 = \$30,000
Solution to Problem #1 (2)

• Volvo
–   TVCVolvo = 10,000 * 200,000 = \$2,000,000,000
–   Total cost (TC) = Total variable cost + Total fixed cost
–   TCVolvo = \$2,000,000,000 + \$1,000,000,000 = \$3 billion
–   ACVolvo= \$3.0 billion / 200,000 = \$15,000
• Why Volvo’s average cost is only half of Saab’s even if they
actually face the same fixed and marginal costs?
• Volvo’s annual production is 4 times larger than Saab’s
• This reveals that Volvo has a much higher market share than
Saab, and thus it has a higher potential for growth relative to
Saab
Problem #3, Chapter 9

• Multiple-choice question
• A single-price, profit maximizing monopolist:
– Causes excess demand, or shortages, by selling too few units of a good
or service
– Choose the output level at which marginal revenue begin to increase
– Always charge a price above the marginal cost of production
– Also maximizes marginal revenue
– None of the above statements is true
Solution to Problem #3, (1)
• A) False
• Even if a monopoly produces less than the perfectly
competitive quantity, it will not produce any excess demand
or shortage
• At the chosen output, demand and supply coincide

• B) False
• A monopoly maximizes the total profit instead
• Similar to a perfectly competitive firm, a monopoly produces
at a level where marginal revenue is equal to marginal cost
Solution to Problem #3 (2)

• C) True
• A monopoly determines an output level by equating marginal
revenue and marginal cost, but it charges a price according to
the demand
• Demand function is always higher than the marginal revenue
function
• Thus, a monopoly always charges a price is greater than the
marginal revenue (marginal cost)
Solution to Problem #3 (3)

• D) False
• A monopoly maximizes the total profit instead
• It actually produces at a level where marginal revenue is equal
to marginal cost

• E) False, as only C is proven to be a true statement
Problem #5, Chapter 9

• Explain why price discrimination and the existence of slightly
different variants of the same product tend to go hand in
hand. Give an example from your own experience.
Solution to Problem #5 (1)

• To capture a higher profit for itself, a monopoly produces less
than the perfectly competitively output
• If it is legal, a monopoly will set a number of prices for a
number of slightly differentiated products
• A monopoly can earn a higher profit by setting a pricing
strategy that is able to identify different types of customer
• This pricing strategy requires so much information,
particularly the distinctive characteristics and reservation
price of the customers
Solution to Problem #5 (2)

• When customers’ reservation prices are identified, a
monopoly can then produce products that are slightly
different from each other
• The differentiation should reveal the distinctive characteristics
of the types of customer so that customers can self-select to
the differentiated products
• As a result, price discrimination and existence of slightly
different variants of the same product always come hand in
hand
Solution to Problem #5 (3)
• Example
• Automobile
• A typical automobile often comes in three options available to
choose from
• The options are very similar to each other, but they are sold in
three level of prices
• The cheapest option- a basic vehicle with manual
transmission and no stereo system and air conditioner
• The moderate option- a basic vehicle with auto transmission,
stereo system, air conditioner and other automotive features,
such as power seats and power locks
Solution to Problem #5 (4)

• The most expensive option- a basic vehicle with all the
features available on the moderate option plus some
luxurious touches like sunroof and leather seats
• Low-income drivers tend to choose the cheapest option
• Average-income drivers tend to choose the moderate option
• High-income drivers tend to choose the most expensive
option
• The monopoly is thus able to earning a profit by serving three
types of customer with a differentiated product
Problem #7, Chapter 9 (1)

• TotsPoses, Inc., a profit maximizing business, is the only
photography business in town that specializes in portraits of a
small children. George, who owns and runs TotsPoses, expects
to encounter an average of eight customers per day, each with
a reservation price shown in the following table.
Problem #7, Chapter 9 (2)

• A) If the total cost of each   Customer   Reservation price
photo portrait is \$12, how                  (\$ per photo)
much should George charge?        A              50
At this price, how many
portraits will George             B              46
produce each day? What            C              42
will be his economic profit?
D              38
E              34
F              30
G              26
H              22
Solution to Problem #7 (1)

Customer (A)    Reservation      Total revenue     Marginal
price (\$/photo)       (\$/day)        revenue
(B)         (# of A) * (B)   (\$/photo)
A               50                50             50
B               46                92             42
C               42               126             34
D               38               152             26
E               34               170             18
F               30               180             10
G               26               182             2
H               22               176             -6
Solution to Problem #7 (2)

• As a monopoly, George will produce at a level where marginal
revenue = marginal cost
• Given that the total (marginal) cost of each portrait is \$12
• Based on the above table, George will set a price that is
consistent with serving only the first five customers
• That is the reservation price of the fifth customer, \$34
• At \$34, George earns an economic profit as follows
– = Total revenue – total cost
– = (\$34 * 5) – (\$12 * 5) = \$170 - \$60
– = \$110 per day
Solution to Problem #7 (3)

• B) How much consumer surplus is generated each day at this
price?
• At \$34, the consumer surplus:
– Difference between sum of reservation prices and total revenue
– (\$50 + \$46 + \$42 + \$38 + \$34) – (\$34 * 5)
– \$40 per day
Solution to Problem #7 (4)

• C) What is the socially efficient number of portraits?
– If there is no positive or negative externality, the socially efficient
output is the perfectly competitive output
– That is P = MC = MR
– Since the marginal cost is less than all of the reservation prices,
George should serve all the customers
– 8 portraits are the socially efficient output
Solution to Problem #7 (5)

• D) George is very experienced in the business and knows the
reservation price of each of his customers. If he is allowed to
charge any price he likes to any consumer, how many portraits
will he produce each day, and what will his economic profit be?
• First degree price discrimination
• George will serve all the customers as the marginal cost is less
than all the reservation prices
Solution to Problem #7 (6)

• George should charge a price according to each customer’s
reservation price
• As long as price is less than or equal to the customer’s
reservation price, the customer is still willing to buy the
portrait
• Monopolistic profit
– = Sum of reservation prices – total cost
– = (\$50 + \$46 + \$42 + \$38 + \$34 + \$30 + \$26 + \$22) – (\$12 * 8)
– = \$192 per day
Solution to Problem #7 (7)

• E) In this case, how much consumer surplus is generated each
day?
• If George charges a price according to the reservation price,
he will capture all the consumer surpluses as monopolistic
profit
• Thus, there will be no consumer surplus
Solution to Problem #7 (8)

• F) Suppose George is permitted to charge two prices. He
knows that customers with a reservation price above \$30
never bother with coupons, whereas those with a reservation
price of \$30 or less always use them. At what level should
George set the list price of a portrait? At what level should he
set the discount price? How many photo portraits will he sell
at each price?
Solution to Problem #7 (9)
• Second degree price discrimination
• There are two markets
• Again, since the marginal cost is lower than all the reservation
prices, serving all customers is profitable!
• George should charge a list price for which the reservation
price is slightly more than \$30
• By setting the list price at \$34, George will have 5 customers
willing to purchase a portrait
• For the discounted market, George should set the discount
price that is equal to the lowest reservation price
Solution to Problem #7 (10)

• By setting the discount price at \$22, George will have 3
customers willing to use the coupon and purchase a portrait
• Charging at these two particular prices, George will be able to
serve all the customers profitably
• The value of the coupon should be
– list price (\$34) - lowest reservation price (\$22) = \$12
Solution to Problem #7 (11)

• In this case, what is George’s economic profit, and how much
consumer surplus is generated each day?
• Economic profit
– =(\$34 * 5) + (\$22 * 3) – (\$12 * 8)
– \$140 per day
• Consumer surplus
– Consumer surplus from customers using and not using coupons
– Sum of reservation prices – total revenue
– (\$50 + \$46 + \$42 + \$38 + \$34) – (\$34 * 5) + (\$30 + \$26 + \$22) – (\$22 *
3)
– \$52 per day
Problem #9, Chapter 9

In the preceding                                                MC
60
question, how much total
surplus would result if
Serena could act as a

\$ per ounce
40
perfectly price
discriminating                           30
monopolist?
20

10

MR         D
0
8    12          24
Ounces/day
Solution to Problem #9 (1)
• A perfectly discriminating monopolist would sell according to
each buyer’s reservation price (Similar to part E of Problem #7)
• The marginal revenue curve and the demand curve become
the same
• Serena would then produce at the perfectly competitive level,
which is 12 ounces per week
• Serena completely captures the consumer surplus by
targeting each buyer’s reservation price; there will be no
consumer surplus
Solution to Problem #9 (2)

• The total surplus is thus                                        MC
60
the area under the
demand curve but
above the supply curve

\$ per ounce
40
at 12 ounces per day
• = (\$60 - \$0) * 12                         30
ounces * 1/2
20
• = \$360 per day
10

MR         D
0
8    12          24
Ounces/day

```
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