# 7.2 The structure of costs in the short run  (Page 5/23)

 Page 5 / 23

Whatever the firm’s quantity of production, total revenue must exceed total costs if it is to earn a profit. As explored in the chapter Choice in a World of Scarcity , fixed costs are often sunk costs    that cannot be recouped. In thinking about what to do next, sunk costs should typically be ignored, since this spending has already been made and cannot be changed. However, variable costs can be changed, so they convey information about the firm’s ability to cut costs in the present and the extent to which costs will increase if production rises.

## Why are total cost and average cost not on the same graph?

Total cost, fixed cost, and variable cost each reflect different aspects of the cost of production over the entire quantity of output being produced. These costs are measured in dollars. In contrast, marginal cost, average cost, and average variable cost are costs per unit. In the previous example, they are measured as cost per haircut. Thus, it would not make sense to put all of these numbers on the same graph, since they are measured in different units ($versus$ per unit of output).

It would be as if the vertical axis measured two different things. In addition, as a practical matter, if they were on the same graph, the lines for marginal cost, average cost, and average variable cost would appear almost flat against the horizontal axis, compared to the values for total cost, fixed cost, and variable cost. Using the figures from the previous example, the total cost of producing 40 haircuts is $320. But the average cost is$320/40, or \$8. If you graphed both total and average cost on the same axes, the average cost would hardly show.

Average cost tells a firm whether it can earn profits given the current price in the market. If we divide profit by the quantity of output produced we get average profit    , also known as the firm’s profit margin . Expanding the equation for profit gives:

But note that:

Thus:

This is the firm’s profit margin . This definition implies that if the market price is above average cost, average profit, and thus total profit, will be positive; if price is below average cost, then profits will be negative.

The marginal cost of producing an additional unit can be compared with the marginal revenue gained by selling that additional unit to reveal whether the additional unit is adding to total profit—or not. Thus, marginal cost helps producers understand how profits would be affected by increasing or decreasing production.

## A variety of cost patterns

The pattern of costs varies among industries and even among firms in the same industry. Some businesses have high fixed costs, but low marginal costs. Consider, for example, an Internet company that provides medical advice to customers. Such a company might be paid by consumers directly, or perhaps hospitals or healthcare practices might subscribe on behalf of their patients. Setting up the website, collecting the information, writing the content, and buying or leasing the computer space to handle the web traffic are all fixed costs that must be undertaken before the site can work. However, when the website is up and running, it can provide a high quantity of service with relatively low variable costs, like the cost of monitoring the system and updating the information. In this case, the total cost curve might start at a high level, because of the high fixed costs, but then might appear close to flat, up to a large quantity of output, reflecting the low variable costs of operation. If the website is popular, however, a large rise in the number of visitors will overwhelm the website, and increasing output further could require a purchase of additional computer space.

For other firms, fixed costs may be relatively low. For example, consider firms that rake leaves in the fall or shovel snow off sidewalks and driveways in the winter. For fixed costs, such firms may need little more than a car to transport workers to homes of customers and some rakes and shovels. Still other firms may find that diminishing marginal returns set in quite sharply. If a manufacturing plant tried to run 24 hours a day, seven days a week, little time remains for routine maintenance of the equipment, and marginal costs can increase dramatically as the firm struggles to repair and replace overworked equipment.

Every firm can gain insight into its task of earning profits by dividing its total costs into fixed and variable costs, and then using these calculations as a basis for average total cost, average variable cost, and marginal cost. However, making a final decision about the profit-maximizing quantity to produce and the price to charge will require combining these perspectives on cost with an analysis of sales and revenue, which in turn requires looking at the market structure in which the firm finds itself. Before we turn to the analysis of market structure in other chapters, we will analyze the firm’s cost structure from a long-run perspective.

## Key concepts and summary

In a short-run perspective, a firm’s total costs can be divided into fixed costs, which a firm must incur before producing any output, and variable costs, which the firm incurs in the act of producing. Fixed costs are sunk costs; that is, because they are in the past and cannot be altered, they should play no role in economic decisions about future production or pricing. Variable costs typically show diminishing marginal returns, so that the marginal cost of producing higher levels of output rises.

Marginal cost is calculated by taking the change in total cost (or the change in variable cost, which will be the same thing) and dividing it by the change in output, for each possible change in output. Marginal costs are typically rising. A firm can compare marginal cost to the additional revenue it gains from selling another unit to find out whether its marginal unit is adding to profit.

Average total cost is calculated by taking total cost and dividing by total output at each different level of output. Average costs are typically U-shaped on a graph. If a firm’s average cost of production is lower than the market price, a firm will be earning profits.

Average variable cost is calculated by taking variable cost and dividing by the total output at each level of output. Average variable costs are typically U-shaped. If a firm’s average variable cost of production is lower than the market price, then the firm would be earning profits if fixed costs are left out of the picture.

## Problems

Return to [link] . What is the marginal gain in output from increasing the number of barbers from 4 to 5 and from 5 to 6? Does it continue the pattern of diminishing marginal returns?

Compute the average total cost, average variable cost, and marginal cost of producing 60 and 72 haircuts. Draw the graph of the three curves between 60 and 72 haircuts.

what is the condition of a consumer behaviour in the equilibrium under the theory of consumer behaviour
what is equilibrium
Sahr
A point where quantity demand & supply meets called equilibrium
Hasham
a state is said to be equilibrium when there is no tendency of movement.
Nibedita
Pls @Nibedita am confused
Prince
The state of balance achieved by an end user of products that refers to the amount of goods and services they can purchase given their present level of income and the current level of prices. Consumer equilibrium allows a consumer to obtain the most satisfaction possible from their income.
Okwori
where is the calculations?
what are the two conditions for aconsumer to be in the equilibrium under the theory of consumer behaviour in
Sahr
Economic equilibrium is a condition or state in which economic forces are balanced. In effect, economic variables remain unchanged from their equilibrium values in the absence of external influences. Economic equilibrium may also be defined as the point at which supply equals demand for a product,
vinay
Hello there, let's make a time to chat about econimics and its issues.
it's true
hie Sir /Madam l need help when it comes to Economics lm doing it for the first time
Thembelani
So, share your problems that you have in terms of economis and we will discuss on it.
DA
Basic Economic problems
Thembelani
what is the Basic Economic problem
Thembelani
what is the Basic Economic problem
scarcity
Rhaiymornd
a bit of explanation please its my first year doing Economics
Thembelani
rare, limited. economic agents eg You dube, the govt & the business entities wants to maximise their utility/satisfaction but because limited resource or scarcity of such resources they are unable to satisfy their needs.
ian
thank u Sir , l understand what you are saying now
Thembelani
limited resources; you wanna take the most benefits from the minimum resource.
DA
if u ar a fresher, eco has to 2 fundamental parts "micro & macro". micro(small) this is were the economc agents ar discussd, economc systms, dmand & supply, typs of market systms etc and the macro (big) part the elucidates the functns of central bank, typs of employmnt, functns of money & int trade.
ian
there is an old adage that says "a picture is worth a thousand words" economics is full of graphing so it requires on the side of the student to master the art of keeping information in form graphs.
ian
oky Sir
Thembelani
scarcity becomes the fundamental problem of economics because of limited resources, when we take an individual, he or she has many wants, thus unlimited wants but can never satisfy all but only few.
Rhaiymornd
now when we take a firm, a firm maybe willing to produce two or more product into the market but due to limited resources they only produce one. the same way if we take the government, he or she maybe willing to bring development either through infrastructures,
Rhaiymornd
that is when consumer decision making rule comes in
Olusegun
choice arises as a result of scarcity of resources
Olusegun
so if we look through, the individual, firm and government, their wants are unlimited but due limited resources, all of their wants cannot be satisfy. therefore scarcity can be term as limited in supply of resources. scarcity is not lack of resources but insufficient resources
Rhaiymornd
there is a marriage with the following; scarcity, factors of production, opportunity cost curve (occ) or (ppc, ppf, tc) production possibility curve productn possibility frontier transformation curve. The OCC, PPC, PPF & TC explains the decisions made by householders, firms & the govt.
ian
opportunity cost also arises as a result of firm willing to produce a particular commodity but resources use in satisfying or producing such output is limited
Olusegun
wat ar those decisions? the most important is WHY nations economise tht is if they hav abundancy of factors of productn eg land, labour & entreprise? now since all of us have unlimited needs against few resourcs PPC, PPF, TC, OCC walks in to make wise allocatn of resources.
ian
how do those decisions made? eg by economic agents; a. Household (You) - if u have R10 & wish to buy a book & a pen & realise that both commodities seĺl at the same price which of the two (2) can u buy (necesity) and which one can u forgo (not all tht important).
ian
b. firms - they allocat mo resourcs to all thoz commoditz tht they think will yield mo profit. c. Govt - if the govt SA was to come in yo area which 1 would u think they can consider first tht can benefit the majority & the minority. So instead of building football stadium they construct a hospital.
ian
if the SA govt had enough resources they would have built both the stadium and the hospital but because of scarce in terms of resources they had to forgo the construction the stadium to build a hospital which is necessary for the majority to benefit.
ian
Opportunity cost well broken down..
Andres
opportunity cost means the lose of other alternatives when the alternative is chosen
is the benefits that you loose by not selecting a certain alternative.
EDWINY
individual wants maybe unlimited, but means to satisfy them are limited there one has to forgo some alternative in order to acquire other alternative and it must according priority, that is when scale of preference set in for individuals to make choice
Rhaiymornd
hello everyone
Aliyu
Next best alternative forgiven
Shoaib
demand is the amount of goods and services that consumer is willing and able to purchase at a particular prices over given period of time
yep
Abraham
what's demand?
What customers want the most...
Abraham
not only what customers wants, want is just mere desire but demand is backed by purchasing power, ability and willingness
Rhaiymornd
thanks
Abraham
What's opportunity cost?
Abraham
what are the differences between demand and supply
who is called lender of the last resort
Hi
Linda
hlw
Karishma
Central bank
Majeed
hy
Karishma
Hello
Majeed
hy
Karishma
How are you
Majeed
Am gud
Linda
fine
Karishma
Am gud
Linda
hello
Chandra
Well! what's going on
Majeed
r u study in economics
Karishma
anybody there?
Chandra
r u study in economics
Karishma
the central bank
Sessay
Majeed
hey
neha
yes
Abigail
Yesss
Majeed
ok
Karishma
hey
Doctor
yh
Abigail
more questions
Sessay
how ar you
Doctor
split the price effect into income effect and substitution effect
Karishma
fine and u
Abigail
Hi
Godwin
hi
Hey, I am new here. Hope, discussion on Economics will clear our concepts more.
yasir
yes
Abigail
do u speak hindi or english
Karishma
how to consumer equlibrium through ic
Karishma
consumer equilibrium demand equals supply
Kenneth
the consumer is in equilibrium when the indifference curve is tangential to the budget line. or when the BL and IC intersect
Sessay
reasons indifference curve slopes downwards?
Kenneth
fine Abby any good,
Doctor
ur lost
Doctor
hey. im new year. economics teacher how we can discuss some thing interesting.
EDWINY
which one
Doctor
what do u understand the concept of poverty cycle.
EDWINY
hey
Ebong
I'm New here
Ebong
hi
ian
just new here guy's and also an Economics fresher of Kogi State University Anyigba
nelson
wxup
Ayegba
who can tell the laboratory of economic?
Amara
, Dennis Weissman Associates, LLC Laboratory Economics is the monthly business newsletter that gets behind the headlines and press releases.
Ayegba
sooo teah me what an LLC
Emmanuel
what's the topic
economic systems
gracious
hello
Antonio
market
aba
hello where can I find the diagrams
Manu
Hello I am totally out ,I am not understanding why we are here. can someone help me out?
Amara
why Economic is not a pure science can someone help me out
Mohamed
because economics like science put forth a some hypotheses and then do experiments to prove them
Anwesh
but these experiments are not completely controlled
Anwesh
Hello
Comfort
hey
suraj
hi people can you help me out on "demand and supply"
Milton
Am not understanding can someone enlighten me pls
Bertilla
hi people can you help me out on "demand and supply"
Sessay
hello. if Mr.Patrick's income is #900.00 while that of Mr.Shodawe is #1300.00 if Mr.Patrick and Shodowe pay #90.00 and #130.00 as taxes,the tax system is?
Benjamin
Benjamin
regressive tax system
shaikh
OK thanks
Benjamin
Isn't this called proportional tax rate because the rate stays the same - 10%? Tell me if I'm wrong
Ioan
Supply is perfectly elastic and demand increases.
whose there
Waseem
show the demand curve
it slopes downward from left to right
Ama
how resources are allocated in a free economy
explain how discriminating Monopoly increase profits
Charlotte
factors responsible for the emergence of monopoly situation
total output produced by a country over a given period of time .... can someone give me the term plz
GDP
Anjorin
thaks man
TMM
Woman. 👍👍
Anjorin
gross domestic products
janet
GDP
Bertilla
GDP
Prof
GDP
Bertilla
gross domestic product
gross domestic product
GDp
Mohamed
gdp
agboola
what is recession pertaining to GDP
Prince
what is recession pertaining to GDP
Prince
what is recession
Prince
law of demand and supply
Zakariyah
All thing been equal
Temple
no i think recession is pertaining to GNP
owolabi
gross national production
Abraham
what is embago
Peter
all things being equal
Raphael
embargo restriction on trade by government of a country
owolabi
an official ban on trade or other commercial activity with a particular country.
Ayegba
Embargo.....an order by a common carrier or publ regulatory agency prohibiting or restric freight transportation
Ayegba
it's a complete band on important n export
Bertilla
who is Really Good in Mathematics. put me Through. Let Do Group Reading; am Preparing to Write Jamb this Year.
Andrew
Hi. C+I+G+x-m
Shoaib
Gdp aggregate demand are bit same
Shoaib
Dpd = c+i+g+(x-m) is aggregate demand
Shoaib
Gdp=c+i+g+(x-m) is aggregate demand
Shoaib
GDP= c+i+s+g+(x-m)
Saboor
Topic ended waiting for next topic
Shoaib
What is Terms of Trade (TOT)?
At what point a Terms of Trade can be favorable?
Define Expansion path
Girma
The difference between cyclical unemployment and structural unemployment
Cyclical unemployment .it has to do with an increase in the quantity of good demanded or there is over production which result in fall in prices. Industries will be affected it will now causes retrenchment of workers in the industries while structural unemployment arises as a result of slight change
In the industrial structure of a countries workers wil now be retren
Will now be retrenched as a result of economic recession... That is the little i knw....