ECON107
Principles of
Microeconomics
Week 11
Chapter-11
11w/11/2013
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Dr. Mazharul Islam

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Dr. Mazharul Islam 11w/11/2013

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Distinguish between the short run and the long run
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Explain the relationship between a firm’s output and labor employed in the shortrun.
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Explain and illustrate a firm’s short-run product curves
11w/11/2013 Dr. Mazharul Islam

11w/11/2013
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The three decisions that all firms must make include:
1.
How much output to supply
2.
Which production technology to use
3.
How much of each input to demand
Dr. Mazharul Islam

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Economic Costs:
A firm’s economic costs are the opportunity costs of the resources used, whether those resources are owned by others or by the firm.
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Economic Costs = Explicit costs + Implicit costs
Explicit costs
Refer to the firm’s actual cash payments for resources owned by others  wages, rent, interest, insurance, taxes, etc.
11w/11/2013 Dr. Mazharul Islam

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Implicit costs:
Refer to the opportunity costs of using its self-owned, self-employed resources.
Implicit costs are the money payments that self-employed resources could have earn in their best alternative use.
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Total Revenue:
It is the amount received from the sale of the product; it is equal to the number of units sold (Q) times the price received per unit (P). So TR = P x Q
11w/11/2013 Dr. Mazharul Islam

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Khaleed operates a small furniture firm.
He hires one assistant at SR21,000 per year, pays annual rent of SR5000 a year for his shop, an invested SR20,000 from his savings on materials that could have earn him SR1000 per year as interest rate. He has been offered SR24,000 per year to work as a manager for competitor.
He estimates his entrepreneurial talents are worth SR3000 per year. Total annual revenue from furniture sales is SR100,000.
11w/11/2013 Dr. Mazharul Islam

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Economic Profits:
Refer to the difference between total revenue and economic costs.
Economic Total
Economic Cost
Profit Revenue
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Production Function:
The relationship between the amount of resources employed and a firms total product is called firm’s production function.
11w/11/2013 Dr. Mazharul Islam

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All decisions can be placed in two time frames:
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
The short run
The long run
11w/11/2013 Dr. Mazharul Islam

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Short Run
The short run is a time frame in which the quantity of at least one resource used in production is fixed.
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For most firms, the capital, called the firm’s plant, is fixed in the short run.
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Other resources used by the firm (such as labor, raw materials, and energy) can be changed in the short run.
Short-run decisions are easily reversed.
11w/11/2013 Dr. Mazharul Islam

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Long Run
The long run is a time frame in which the quantity of all resource used in production is variable.
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Long-run decisions are not easily reversed.
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Variable resources can be varied quickly to change the output rate.
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Fixed resources are those resources which cannot be easily changed.
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
To increase output in the short run, a firm must increase the amount of labor employed because technology is constrained.
Three concepts describe the relationship between output and the quantity of labor employed:
1. Total product
2. Marginal product
3. Average product
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
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Total Product (TP): It means total quantity or total output of a particular good produced in a given period.
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Marginal Product (MP): it is extra output associated with adding an unit of variable resource (in this case, labor) to production process while all other inputs remaining the same.
Marginal Product =
Change in Total Product
Change in Labor Input
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
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Average Product (AP): It is called labor productivity. The output of per unit of resource (in this case per unit labor output).
Total Product
Average Product =
Units of Labor
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
Table 11.1
shows a firm’s product schedules. As the quantity of labor employed increases:
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Total product increases.
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Marginal product increases initially but eventually decreases.
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Average product decreases.
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
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Increasing marginal returns: The marginal products of a variable resource (labor) increases as each additional unit of that resource is employed.
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Increasing marginal returns arise. Why?
Due specialization and division of labor.
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Law of diminishing marginal return states that the more of a variable resource is added with a given amount of a fixed resource, other things constant, marginal product eventually declines and could become negative.
11w/11/2013 Dr. Mazharul Islam

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Short-Run Production Relationships
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Diminishing marginal returns arises.
Why?
Because each additional worker has less access to capital and less space in which to work.
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5w/9/2013 Dr. Mazharul Islam