# 7.3 The structure of costs in the long run  (Page 3/26)

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[link] illustrates the idea of economies of scale, showing the average cost of producing an alarm clock falling as the quantity of output rises. For a small-sized factory like S, with an output level of 1,000, the average cost of production is $12 per alarm clock. For a medium-sized factory like M, with an output level of 2,000, the average cost of production falls to$8 per alarm clock. For a large factory like L, with an output of 5,000, the average cost of production declines still further to \$4 per alarm clock.

The average cost curve in [link] may appear similar to the average cost curves presented earlier in this chapter, although it is downward-sloping rather than U-shaped. But there is one major difference. The economies of scale curve is a long-run average cost curve, because it allows all factors of production to change. The short-run average cost curves presented earlier in this chapter assumed the existence of fixed costs, and only variable costs were allowed to change.

One prominent example of economies of scale occurs in the chemical industry. Chemical plants have a lot of pipes. The cost of the materials for producing a pipe is related to the circumference of the pipe and its length. However, the volume of chemicals that can flow through a pipe is determined by the cross-section area of the pipe. The calculations in [link] show that a pipe which uses twice as much material to make (as shown by the circumference of the pipe doubling) can actually carry four times the volume of chemicals because the cross-section area of the pipe rises by a factor of four (as shown in the Area column).

Comparing pipes: economies of scale in the chemical industry
Circumference ( $2\pi r$ ) Area ( $\pi {r}^{2}$ )
4-inch pipe 12.5 inches 12.5 square inches
8-inch pipe 25.1 inches 50.2 square inches
16-inch pipe 50.2 inches 201.1 square inches

A doubling of the cost of producing the pipe allows the chemical firm to process four times as much material. This pattern is a major reason for economies of scale in chemical production, which uses a large quantity of pipes. Of course, economies of scale in a chemical plant are more complex than this simple calculation suggests. But the chemical engineers who design these plants have long used what they call the “six-tenths rule,” a rule of thumb which holds that increasing the quantity produced in a chemical plant by a certain percentage will increase total cost by only six-tenths as much.

## Shapes of long-run average cost curves

While in the short run firms are limited to operating on a single average cost curve (corresponding to the level of fixed costs they have chosen), in the long run when all costs are variable, they can choose to operate on any average cost curve. Thus, the long-run average cost (LRAC) curve    is actually based on a group of short-run average cost (SRAC) curves , each of which represents one specific level of fixed costs. More precisely, the long-run average cost curve will be the least expensive average cost curve for any level of output. [link] shows how the long-run average cost curve is built from a group of short-run average cost curves. Five short-run-average cost curves appear on the diagram. Each SRAC curve represents a different level of fixed costs. For example, you can imagine SRAC 1 as a small factory, SRAC 2 as a medium factory, SRAC 3 as a large factory, and SRAC 4 and SRAC 5 as very large and ultra-large. Although this diagram shows only five SRAC curves, presumably there are an infinite number of other SRAC curves between the ones that are shown. This family of short-run average cost curves can be thought of as representing different choices for a firm that is planning its level of investment in fixed cost physical capital—knowing that different choices about capital investment in the present will cause it to end up with different short-run average cost curves in the future.

what happens when maximum price is placed above equilibrium price
the demand curve falls
Ewerton
explain the term : law of demand and it's function
law of demand state that the higher the price the lower the quantity demanded and vice versa
Moka
Está correto, sua função também é a de estabilizar o mercado do produto em questão, seu preço, sua produção, etc.
Ewerton
higher******
Umar
what are raw materials
the basic material from which a product is made. "these could be used as raw material"
fatmah raw material, also known as a feedstock, oky is a basic material that is used to produce goods, finished products, energy, or intermediate materials that are feedstock for future finished products. just to make outputs.
oh yeah I got it .. thank you for your help 😊
Fatmah
hello my dear friends
Au
hello
Fatmah
hello
hy
Sortema
Any notes on ppf.?
George
can anyone clarify features of internal efficiency with reference to education
Sortema
in an open economy, the GDP is measured as ?
what is Labour of supply.
it is called supply of labour
Emmanuel
it is the total number of those the producer is expected to employ at a given time and at an existing wage rate
Emmanuel
it is a sum number of employees the manufacturer wish to employ in a period of time , and at a given wage rate
Evacon
if the price of yam increases what will happen to demand curve?
the demand curve will decrease
Fatmah
with table and diagrametic illustration
ok
Mustafe
if the price elasticity of demand for a commodity is zero the demand curve is
the demand curve is inelastic
Emmanuel
this is because price bring about a lesser change in quantity demanded
Emmanuel
how are we going to draw scale of preference
how do we identify choice
Achor
how do we identify opportunity cost
Achor
opportunity cost is the forgone alternative. in oder words, it is the sacrificed goods or service for another. thus, the item you did not buy with the resources you have thereby buying another one is called opportunity cost. thanks
John
Opportunity cost considers only the next best alternative to an action, not the entire set of alternatives, and takes into account all of the differences between the two choices.
IAC curve is geueraly
what are the benefits or tourism?
please I don't understand the division of labor increase
Labour increasing according to demand of company or as the condition of profit and standards or weight of working level ,,,,
SHOM
Please can someone help me With the demand of labour.
Eshmel
what are the basic concept of economics
end mean and scarcity
Dery
What the term economics?
economic is the study of mankind in the ordinary business life
Dery
want to find how can a geography teacher can contribute to the economic development of a country .
how are u
Usama
i am fine
Purnima
it can help to prevent world wars 😂😂😂😂
Vedaant
it can help to prevent world wars 😂😂😂😂
Vedaant