Finding Percent Change

Learning Outcomes

  • Find percent change (increase or decrease

People in the media often talk about how much an amount has increased or decreased over a certain period of time. They usually express this increase or decrease as a percent.

To find the percent change, first we find the amount of change, which is the difference between the new amount and the original amount. Then we find what percent the amount of change is of the original amount.

Find Percent CHANGE

Step 1. Find the amount of change.

  • [latex]\text{increase}=\text{new amount}-\text{original amount}[/latex]

Step 2. Divide the amount of change found in Step 1 by the original amount (this will result in a decimal).

Step 3. Convert the decimal found in Step 2 to a percentage by multiplying by 100.  Add the percent symbol %.

If the answer is negative, the change is a decrease. The answer must include either a negative sign or the word decrease, but not both.

If the answer is positive, the change is an increase.

 

example

In [latex]2011[/latex], the California governor proposed raising community college fees from [latex]\text{\$26}[/latex] per unit to [latex]\text{\$36}[/latex] per unit. Find the percent change. (Round to the nearest tenth of a percent.)

Solution

 

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example

The average price of a gallon of gas in one city in June [latex]2014[/latex] was [latex]\text{\$3.71}[/latex]. The average price in that city in July was [latex]\text{\$3.64}[/latex]. Find the percent change.

 

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In the following video we show more examples of how to find percent change.