Economics

  1. Home
  2. Education
  3. Economics

Elasticity Practice Question

Caluating Own Price Elasticity

By Mike Moffatt, About.com

c. Calculate the price elasticity of demand for butter at the equilibrium. What can we say about the demand for butter at this price-point? What significance does this fact hold for suppliers of butter?

We know that:

M = 20 (in thousands)
Py = 2
Px = 14
Q = 14000
Q = 20000 - 500*Px + 25*M + 250*Py

From Using Calculus To Calculate Price Elasticity of Demand we see that:

we can calculate any elasticity by the formula:

Elasticity of Z with respect to Y = (dZ / dY)*(Y/Z)

In the case of price elasticity of demand, we are interested in the elasticity of quantity demand with respect to price. Thus we can use the following equation:

Price elasticity of demand: = (dQ / dPx)*(Px/Q)

In order to use this equation, we must have quantity alone on the left-hand side, and the right-hand side be some function of price. That is the case in our demand equation of 20000 - 500*Px + 25*M + 250*Py. Thus we differentiate with respect to P and get:

dQ/dPx = -500

So we substitute dQ/dP = -500, Px=14, and Q = 20000 - 500*Px + 25*M + 250*Py into our price elasticity of demand equation:

Price elasticity of demand: = (dQ / dPx)*(Px/Q)
Price elasticity of demand: = (-500)*(14/20000 - 500*Px + 25*M + 250*Py)
Price elasticity of demand: = (-500*14)/14000
Price elasticity of demand: = (-7000)/14000
Price elasticity of demand: = -0.5

Thus our price elasticity of demand is -0.5.

Since it is less than 1 in absolute terms, we say that Demand is Price Inelastic. This means that consumers are not very sensitive to price changes, so a price hike will lead to increased revenue for the industry.

That's the end of this Q&A. I hope everyone found it useful!

Explore Economics

About.com Special Features

How to Ace the GRE

Being well prepared is the first step; here are more essential suggestions. More >

The Business School Lowdown

Everything from choosing a school and applying, to employment after graduation. More >

Economics

  1. Home
  2. Education
  3. Economics
  4. Macro, Micro, Other Fields
  5. Microeconomics
  6. Elasticity
  7. Price Elasticity of Demand
  8. Elasticity Practice Question

©2009 About.com, a part of The New York Times Company.

All rights reserved.