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This means that, along the demand curve between point B and A, if the price changes by 1%, the quantity demanded will change by 0.45%. A change in the price will result in a smaller percentage change in the quantity demanded. For example, a 10% increase in the price will result in only a 4.5% decrease in quantity demanded. A 10% decrease in the price will result in only a 4.5% increase in the quantity demanded. Price elasticities of demand are negative numbers indicating that the demand curve is downward sloping, but are read as absolute values. The following Work It Out feature will walk you through calculating the price elasticity of demand.

Finding the price elasticity of demand

Calculate the price elasticity of demand using the data in [link] for an increase in price from G to H. Has the elasticity increased or decreased?

Step 1. We know that:

Price Elasticity of Demand = % change in quantity % change in price

Step 2. From the Midpoint Formula we know that:

change in quantity = Q 2 Q 1 ( Q 2 + Q 1 )/2  × 100 change in price = P 2 P 1 ( P 2 + P 1 )/2  × 100

Step 3. So we can use the values provided in the figure in each equation:

% change in quantity = 1,600 1,800 ( 1,600 + 1,800 )/2  ×  100 = –200 1,700  ×  100 = –11 . 76 % change in price = 130 120 ( 130 + 120 )/2  ×  100 = 10 125  ×  100 = 8 . 0

Step 4. Then, those values can be used to determine the price elasticity of demand:

Price Elasticity of Demand = % change in quantity % change in price = –11.76 8 = 1.47

Therefore, the elasticity of demand from G to H 1.47. The magnitude of the elasticity has increased (in absolute value) as we moved up along the demand curve    from points A to B. Recall that the elasticity between these two points was 0.45. Demand was inelastic between points A and B and elastic between points G and H. This shows us that price elasticity of demand changes at different points along a straight-line demand curve .

Calculating the price elasticity of supply

Assume that an apartment rents for $650 per month and at that price 10,000 units are rented as shown in [link] . When the price increases to $700 per month, 13,000 units are supplied into the market. By what percentage does apartment supply increase? What is the price sensitivity?

Price elasticity of supply

The graph shows an upward sloping line that represents the supply of apartment rentals.
The price elasticity of supply is calculated as the percentage change in quantity divided by the percentage change in price.

Using the Midpoint Method ,

% change in quantity = 13,000 10,000 ( 13,000 + 10,000 )/2  × 100 = 3,000 11,500  × 100 = 26.1 % change in price = $700 $600 ( $700 + $650 )/2  × 100 = 50 675  × 100 = 7.4 Price Elasticity of Supply = 26.1%   7.4% = 3.53

Again, as with the elasticity of demand, the elasticity of supply is not followed by any units. Elasticity is a ratio of one percentage change to another percentage change—nothing more—and is read as an absolute value. In this case, a 1% rise in price causes an increase in quantity supplied of 3.5%. The greater than one elasticity of supply means that the percentage change in quantity supplied will be greater than a one percent price change. If you're starting to wonder if the concept of slope fits into this calculation, read the following Clear It Up box.

Is the elasticity the slope?

It is a common mistake to confuse the slope of either the supply or demand curve with its elasticity. The slope is the rate of change in units along the curve, or the rise/run (change in y over the change in x). For example, in [link] , each point shown on the demand curve, price drops by $10 and the number of units demanded increases by 200. So the slope is –10/200 along the entire demand curve and does not change. The price elasticity, however, changes along the curve. Elasticity between points A and B was 0.45 and increased to 1.47 between points G and H. Elasticity is the percentage change, which is a different calculation from the slope and has a different meaning.

When we are at the upper end of a demand curve, where price is high and the quantity demanded is low, a small change in the quantity demanded, even in, say, one unit, is pretty big in percentage terms. A change in price of, say, a dollar, is going to be much less important in percentage terms than it would have been at the bottom of the demand curve. Likewise, at the bottom of the demand curve, that one unit change when the quantity demanded is high will be small as a percentage.

So, at one end of the demand curve, where we have a large percentage change in quantity demanded over a small percentage change in price, the elasticity value would be high, or demand would be relatively elastic. Even with the same change in the price and the same change in the quantity demanded, at the other end of the demand curve the quantity is much higher, and the price is much lower, so the percentage change in quantity demanded is smaller and the percentage change in price is much higher. That means at the bottom of the curve we'd have a small numerator over a large denominator, so the elasticity measure would be much lower, or inelastic.

As we move along the demand curve, the values for quantity and price go up or down, depending on which way we are moving, so the percentages for, say, a $1 difference in price or a one unit difference in quantity, will change as well, which means the ratios of those percentages will change.

Key concepts and summary

Price elasticity measures the responsiveness of the quantity demanded or supplied of a good to a change in its price. It is computed as the percentage change in quantity demanded (or supplied) divided by the percentage change in price. Elasticity can be described as elastic (or very responsive), unit elastic, or inelastic (not very responsive). Elastic demand or supply curves indicate that quantity demanded or supplied respond to price changes in a greater than proportional manner. An inelastic demand or supply curve is one where a given percentage change in price will cause a smaller percentage change in quantity demanded or supplied. A unitary elasticity means that a given percentage change in price leads to an equal percentage change in quantity demanded or supplied.

Problems

The equation for a demand curve is P = 48 – 3Q. What is the elasticity in moving from a quantity of 5 to a quantity of 6?

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The equation for a demand curve is P = 2/Q. What is the elasticity of demand as price falls from 5 to 4? What is the elasticity of demand as the price falls from 9 to 8? Would you expect these answers to be the same?

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The equation for a supply curve is 4P = Q. What is the elasticity of supply as price rises from 3 to 4? What is the elasticity of supply as the price rises from 7 to 8? Would you expect these answers to be the same?

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The equation for a supply curve is P = 3Q – 8. What is the elasticity in moving from a price of 4 to a price of 7?

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Questions & Answers

What is trade line
Ruchi Reply
what is scars
Siaw Reply
What is land as labour
Siaw
Price and output determination in a monopoly?
Ruchi Reply
Monopoly :its features, measures market power
Ruchi
Monopoly is market structure where he/she is d boss with no competition.Therefore he quote his own price for product as well for quantity he provide. Eg.Suppose desert area only one shop he/she selling 10ltr water bottle @25.But with same amt you could have bought 20ltr if it's perfect competition.
Tactful
Economics is a social sciences that have diverse application
Francis Reply
what is economics?
Osborne Reply
Economic is the study of human behaviour in relation with the scare resources and it alternate use.
Tactful
Economics is a social sciences that have diverse application...
Francis
the branch of knowledge concerned with the production, consumption, and transfer of wealth.
charlon
choice and opportunity cost?
SRIPRIYA Reply
choice is the next best alternative
Taina
Choice is option available. Opportunity cost means giving up other to get The 1st one. eg. U r hungry u got 2option available on fridge A and B. You select A over B. so this is opportunity cost. B is the Opportunity Cost over A.
Tactful
can I get simple language and examples?
Gajendra Reply
what is demand
Yavara Reply
what is fiscal policy
David
fiscal policy can be defined as the use of government's income and expenditure for a specific purpose
Nzenwata
ahhhh.. i dont what is expindetures
ian
It is the policy use by govt to influence economy ( manage inflation and deflation). Steps involved are govt spending and taxation.
Tactful
Demand is quantity of good a person is willing and ready to buy at given period of time at given price.
Tactful
good
abubakar
good but high language
Gajendra
lower the language @gajendra Singh
abubakar
What is natural monopoly
Ruchi
Natural monopoly is a market structure or system where the creation of goods and services, it's distribution and pricing mechanisms are undertaken by a sole firm resulting from demand, economies of scale and existing market survey other than legal constraints.
Gh
I don't really know anything about economics but am offering it at the University....
Oteng
Which uni if I may ask...?
Gh
can u help me guys to answer this question what are the different ways of defining money in your economy? Compare these with the monetary aggregates commonly used in another selected country. Explain their differences and the reasons for such differentiation.
aisyah
Why do we observe a wide variety of checking and savings accounts, rather than just one of each type? What are the reasons for the existence of financial intermediaries? Why do the ultimate lenders usually not lend directly to the ultimate borrowers?
aisyah
what is economic
David
The social science which study human behaviour and relationship between end and scare mean which have alternative uses.
Amadu
Trade line example
Ruchi
@ruchi y have conpleted pg in economics or doing pg in econonics
Ashish
Explain economic growth with the use of ppf?
Michael Reply
what z the meaning of ppf
rivan
do u mean ppc
Nzenwata
Yes pls ppc
Michael
an expansionary fiscal policy could be achieved by what
David
if the price of cigarettes ,food and alcohol rised by 10% in a year ,which is most likely to affect the cpi the most.
David
what measures would be suitable for reducing a recessionary gap.
David
increasing the level of government government expenditure is an instrument of what
David
A reductionin income tax rates would blank the blank of the multiplier
David
progressive taxes may slow down economic recovery .This is as a result of what
David
money acts as a safe guard against inflation something and something one of a function of money
David
A rise in expenditure for consumer goods something and something ,one of the cause of cost- push inflation
David
PPC IS production possibility curve. It show possible good which can be produced by an economy with given resource and technology.
Tactful
Recessionary gap can be solved by Monetary and Fiscal policy
Tactful
What are the positive effects on the economy to legalize drugs?
Richard Reply
wat factor give raise to monopoly
Ebenezer Reply
a product which is unique /it has very less substitutes in the market. so this product has no much competition .... for example , railways
mikey
its a monopoly
mikey
does monology has factors or it has merits n demerits
rivan
monopoly or oligopoly is just a type of market in which demand and supply is measured to meet public interests
mikey
economy is all about psychological behaviour of humans to each other and to environment economists role is to keep everything in equilibrium
mikey
factors give rise to monopoly. 1. Patent right 2. Cartel 3. Govt policy. 4. Control over raw material. 5. money for investment
Tactful
oligopoly and monopoly are examples of imperfect market..
Nzenwata
First, second and third degree price determination under monopoly
Ruchi
please explain what is elasticity of supply
Austine Reply
is the responsiveness of quantity supplied of commodity to changes in its own price
rivan
what is the cause of a country's population
Destiny Reply
please it seems your question is not clear ,is it the cause of increase or decrease population in a country or what
okai
what is producer surplus
Destiny Reply
is the excess earns btn wat a producer was willing to charge for e commodity and wat actually receives after selling it
rivan
OK good
Destiny
yeap
Bright
what is supply curve
Destiny Reply
are curve that do not obey the law of supply eg aren't +ve
rivan
half of 1%
Destiny
as in what do u mean by that
rivan
it simply shows the quantity of goods that a film is willing to supply at each price of a commodity
Destiny
OK what is the law of supply as u said
Destiny
It is the indifference curve that indicates the aggregate responsiveness of supply to the price of a commodity, and sometimes its demand of that same commodity.
Gh
nice
Destiny
pls explain how indifference curve connects to the aggregate responsiveness of supply to the price of a commodity
JOSHUA
law of supply according to me states that wen thea z higher price of commodity, the higher will be the supply and lower the supply will be for a commodity other factors remain constant
rivan
Joshua be clear to your QN plizzz
rivan
pls read Gh's comment and break down for me
JOSHUA
may be he can explain more because am am also not getting what he was meaning in that statement
rivan
plizzz GH explain to us
rivan
When demand and supply intersection
Pronoy
then it z called what
rivan
can I learning what is meaning off economics
Jimcaale
can you tall me what is meaning
Jimcaale
good
abubakar
please oligopoly explan.......
Zahid
in oligopoly there is a competition between companies, becoz all those companies produce almost similar products in monopoly , product has no substitutes in the market for competition, so people have no choice to choose another similar product over this, becoz there is no similar product
mikey
oligopoly : mobile phone manufacturing companies have huge competition over one another
mikey

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Source:  OpenStax, Principles of economics. OpenStax CNX. Sep 19, 2014 Download for free at http://legacy.cnx.org/content/col11613/1.11
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