Understanding Economics
6th edition
by Mark Lovewell
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Chapter 4
Costs of Production
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Learning Objectives

After this chapter you will be able to:
identify economic costs (explicit and implicit) of
production and economic profit
2. recognize short-run (total, average, and marginal)
products, and the law of diminishing marginal returns
3. derive short-run (total, average, and marginal) costs
4. explain long-run results of production (increasing returns
to scale, constant returns to scale, and decreasing returns to
scale) and long-run costs
1.
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Types of Production

There are three main sectors in the economy:
 the primary sector, which consists of industries that
extract or cultivate natural resources
 the secondary sector, which consists of industries that
fabricate or process goods
 the service sector, which consists of trade and
information industries
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Productive Efficiency

Businesses can choose from different production
processes.
 A labour-intensive process employs more labour and
less capital.
 A capital-intensive process employs more capital and
less labour.

The lowest-cost process provides productive efficiency.
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Economic Costs

Economic costs include:
 explicit costs, which are payments to resource supplies
outside a business
 implicit costs, which are what owners give up by being
involved in a business

Economic profit is found by subtracting economic
costs (both explicit and implicit) from total revenue.
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Accounting versus Economic Profit
 Accounting profit is total revenue minus explicit costs.
 Because accountants consider only explicit costs,
accounting profit always exceeds economic profit by
the amount of the business’s implicit costs.
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Production in the Short Run (a)

In the short run:
 some inputs (such as capital) are fixed
 other inputs (such as labour) are variable

Inputs are combined to make total product. Other
product measures include:
 average product, which is total product divided by the
number of workers
 marginal product, which is the extra total product
associated with an additional worker
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The Law of Diminishing Marginal
Returns

Short-run production is determined by the law of
diminishing marginal returns. According to this law:
 the addition of more variable input causes marginal
product to fall after some point
 average product also falls after some point
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Relating Average and Marginal
Values

Average and marginal values are related using three
rules:
 If an average value is rising, then the marginal value
must be above the average value.
 If an average value is falling, then the marginal value
must be below the average value.
 If an average value stays constant, then the marginal
value must equal the average value.
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Total, Marginal, and Average Products
Total
Product
(q)
(workers (T-shirts
per day) per day)
0
0
1
80
2
200
3
250
4
270
5
280
6
270
Marginal
Product
(Δq/ΔL)
(T-shirts
per day)
80
120
50
20
10
-10
Average
Product
(q/L)
(T-shirts
per day)
80
100
83.3
67.5
56
45
300
250
TP
200
150
100
50
0
--
1
2
3
4
5
6
Number of Workers Employed per Day
T-Shirts Produced per Day
Labour
(L)
T-Shirts Produced per Day
Figure 4.2, Page 95 and Figure 4.3, Page 97
Diminishing
returns set in
120
100
80
60
AP
40
20
0
-20
1
2
3
4
5
6
MP
Number of Workers Employed per Day
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Costs in the Short Run

Short-run costs include:
 fixed costs (costs of all fixed inputs)
 variable costs (costs of all variable inputs)
 total cost (fixed costs + variable costs)
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Marginal Cost (a)

Marginal cost is the extra cost of producing another
unit of output.
 It equals the change in total cost divided by the change
in total product.

The marginal cost curve is shaped like a “J” because of
the law of diminishing marginal returns.
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Marginal Cost (b)
Figure 4.6, Page 100
12
MC
10
$ per T-Shirt
8
6
Diminishing
returns set in
4
2
0
50
100
150
200
250
300
Quantity of T-Shirts Produced Per Day
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Per-Unit Costs

Per-unit costs include:
 average fixed cost (fixed costs divided by total product)
 average variable cost (variable costs divided by total
product)
 average cost


either total cost divided by total product
or average fixed cost + average variable cost
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Short-Run Costs for Pure ‘n’ Simple T-Shirts
Figure 4.5, Page 99
Labour
(L)
Total Marginal Fixed Variable
Product Product Costs Costs
(MP)
(q)
(FC)
(VC)
0
0
1
80
2
200
3
250
4
270
5
280
80
120
50
20
10
Average
Marginal Average
Average
Cost
Cost
Fixed Costs Variable
(AC)
(MC)
(AFV)
Costs
(ΔTC/Δq)
(FC/q)
(AVC) (AFC + AVC)
(VC/q)
Total
Cost
(TC)
(FC + VC)
$825
$0
$825
825
140
965
825
300
1125
825
425
1250
825
535
1360
825
640
1465
140
$1.75
160
1.33
125
2.50
110
5.50
105
10.50
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$10.31
$1.75
$12.06
4.13
1.50
5.63
3.30
1.70
5.00
3.06
1.98
5.04
2.95
2.29
5.24
The Family of Short-Run Cost
Curves
Figure 4.7, page 102 12
MC
$ per T-Shirt
10
8
6
AC
b
4
AFC
AVC
2
a
0
50
100
150
200
250
300
Quantity of T-Shirts Produced Per Day
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Returns to Scale (a)

All inputs can be changed by the same proportion in
the long run.
 Increasing returns to scale means the % change in
output > the % change in inputs.
 Constant returns to scale means the % change in output
= the % change in inputs.
 Decreasing returns to scale means the % change in
output < the % change in inputs.
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Returns to Scale (b)



Increasing returns to scale are caused by the division
of labour, specialized capital, or specialized
management.
Constant returns to scale arise whenever making more
of a product means repeating exactly the same tasks.
Decreasing returns to scale are caused by management
difficulties or limited natural resources.
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Costs in the Long Run (a)


Long-run average cost is the minimum short-run
average cost at every output.
The long-run average cost curve is saucer-shaped
because of various ranges of returns to scale:
 an initial range of increasing returns to scale
 a middle range of constant returns to scale
 a final range of decreasing returns to scale
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Costs in the Long Run (b)
Figure 4.8, page 105
Long-Run Average Costs
AC4
$ per Magazine
AC1
AC2
Range A
AC3
Range B
Quantity of Magazines per Week
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Range C
Long-Run AC
Costs in the Long Run (b)
Figure 4.9, page 107
Possible Long-Run Average Costs
Extended Range of
Decrease Returns
to Scale
Extended Range of
Constant Returns
to Scale
Extended Range of
Increasing Returns
to Scale
Quantity of Output
Long-Run AC
Quantity of Output
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$ per Unit
Long-Run AC
$ per Unit
$ per Unit
Long-Run AC
Quantity of Output
Critic of the Modern Corporation

John Kenneth Galbraith:
 suggested that ownership and control are separated in
large corporations
 argued that shareholders (the owners) give up control to
managers
 held out the possibility that managers are more
interested in maximizing sales than in maximizing
profit
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The Profit Game (OLC)
 Economists and accountants differ in the way they
measure business performance.
 For accountants, there are two main business records:
 a balance sheet shows a business’s assets, or items that it
owns. It also lists a business’s liabilities, or items that it
owes, as well as owner’s equity, which is the owner’s
stake in the business
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The Profit Game (OLC) (b)
 An income statement shows a business’s activities in a
given time period, incorporating total sales (or revenue)
and total expenses, which are its explicit costs.
 One important explicit cost is depreciation, or the
reduction in the value of a business’s durable assets.
 For these assets (excluding land), an annual
depreciation charge is included in the income statement
as an expense.
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The Profit Game (OLC)
Income Statement
Income Statement
(for the year)
Total Sales
Expenses
Food
Fuel
Depreciation
Interest on loan
Total explicit costs
$50 000
$ 15 000
3 500
1 000
500
Total profit
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$20 000
$ 30 000
The Profit Game (OLC)
Calculating Economic Profit
Total Revenue
$50 000
Explicit Costs
Food
Fuel
Depreciation
Interest on loan
Total explicit costs
$ 15 000
3 500
1 000
500
Implicit Costs
Owner’s wage
Normal profit
Total implicit costs
$ 25 000
3 000
$20 000
Economic Profit
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$28 000
$ 2 000
Markets in Motion (OLC) (a)
 While bonds are a form of marketable form of interest-
bearing debt, stocks provide their holders with the
opportunity for dividends and stock price
appreciation.
 Stocks have a book value and market value, which
often differ widely. Participants in stock markets look
at P/E ratios, which relate a stock’s market price to the
company’s latest reported earnings. Stocks with high
P/E ratios are considered to be expensive.
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Markets in Motion (OLC) (b)
 The Toronto Stock Exchange (the TSX) is the third
largest in North America, behind the New York Stock
Exchange (NYSE) and NASDAQ (originally the
National Association of Securities Dealers Automated
Quotations system). The TSX concentrates on shares
of relatively large companies in Canada.
 All junior equities (i.e. shares of smaller companies) in
Canada trade on the TSX Venture Exchange, with
headquarters in Calgary, Alberta, and with offices in
Toronto, Vancouver, Winnipeg, and Montreal.
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Markets in Motion (OLC) (c)
 All derivatives in Canada trade on the Montreal
Exchange.
 There are two main types of derivatives:
 Future contracts represent agreements to exchange an
underlying at some future time. So-called hedgers and
speculators participate in the futures market, the first
group in order to protect themselves from changes in
the price of the underlying item and the second to make
a profit. Price variations in futures markets can be
significant.
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Markets in Motion (OLC) (d)
 Options allow their holders to buy or sell an underlying
item during a given time period. There are two types of
options. Call options allow the holder to buy, and put
options to sell, the underlying item. Both are traded by
hedgers and speculators for the same reasons as futures
contracts. Option premiums contain two elements: an
intrinsic value and a time value
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Chapter 4
The End
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