Math CentralQuandaries & Queries


Question from Christine, a student:

For my intermediate macroeconomics class, there is a question about percent change.
The numbers are:
Quantities of oranges in 2010: 104
Quantities of oranges in 2009: 100
How would I calculate to find the percentage change in quantities?

Hi Christine,

If a quantity changes over time the term "percentage change" usually refers to the change, as a percentage of the quantity at the earlier date, where the change is the later quantity minus the earlier quantity. In your case the quantity at the earlier date is 2009 so the earlier quantity is 100, and the change is $104 - 100 = 4.$ Hence the percentage change is

\[\frac{4}{100} \times 100 = 4\%\]


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