<< Chapter < Page Chapter >> Page >

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:

average profit = profit quantity produced = total revenue – total cost quantity produced = total revenue quantity produced total cost quantity produced = average revenue – average cost

But note that:

average revenue = price × quantity produced quantity produced = price

Thus:

average profit = price – average cost

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?

Got questions? Get instant answers now!

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.

Got questions? Get instant answers now!

Questions & Answers

why does a firm continue operating at a breakeven point
Prince Reply
to retain its customers for later coming profits.
tesfie
what economic trend can we expect after lifting of 10 year long sanctions in an national economy?
tesfie Reply
difference between change in demand and change in quantity demanded
Maurice Reply
how
kumar
how to change
kumar
For a demand with repect to price. change in demand refers to the shifting of demand curve, where as change in quantity demanded means movement along the given demand curve.
Farooq
According to lional Robbins how did he explain economics
Raphael Reply
He defined economics as a science which studies human behavior as a relationship between ends and scares which has alternative uses.
Emmanuel
What is economics
Nasiru Reply
why are some countries producing inside the ppf
Claire Reply
prove or disprove that balance of trade of trade deficit is a cause of an abnormal demand curve?
Chioma Reply
what's the fixed cost at output zero
Saidou Reply
fixed cost stay the same regardless of the level of output
Luka
what are the differences between change in demand and change in quantity demand
Sulaiman Reply
what is consumers behaviour
Marfo Reply
importance of income
Emmanuel Reply
Tfor settlement of debt. For purchases. For payment of bills. For daily transactions. For social & recreational enjoyment. For business purposes etc
Oyetunde
thanks
Emmanuel
For investment purposes For security purposes For purpose of forecasting & strategizing.
Oyetunde
what is the real definition of economics
jegede Reply
Economics is the study of the use and allocation of (scarce) resources
demsurf
Jegede, what is the "non" real definition of economics then?
Ernest
Economics is a study of how human use limited resources to fulfil their unlimited want
Musa
the study of how a society use scarce factors of production efficiently so as meet aggregate social demand
Marc
what is oligopoly?
Sailo
Oligopoly can be defines as a market where by there is only tmo or more sellers of a commodity
Paamat
Sory not tmo but two
Paamat
incidence of production there is a choice do you agree? justify
Oduro Reply
What is incidence of production? do u mean incidence of tax?
Aryeetey
I want to know about Richard lipsey and robin as the economist and their definition proposed by them
Musa Reply
what are the causes of scarcity And what are the goal scarcity
Musa
scarcity only exist because human wants are unlimited...if human just know how to be contented then scarcity will not exist
Ylaine
what is ment by possibility curve
Ruzaiq
define accounting?teatly
Ahmed Reply
Is the recording, classifying, interpreting record of all transaction
Yuusuf
is still the act of measuring, interpreting and communicating of financial issues
Yuusuf
measuring business or individual finance
Zeyi
Accounting is the process of collecting,recording,classifying,summarizing and interpreting/presenting financial data to the stakeholders for their economic decision making
asri
hi
Otilina
hi
AVIAH
wat is PPC
ALLAJI

Get the best Principles of economics course in your pocket!





Source:  OpenStax, Principles of economics. OpenStax CNX. Sep 19, 2014 Download for free at http://legacy.cnx.org/content/col11613/1.11
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Principles of economics' conversation and receive update notifications?

Ask