Unit 3, Lesson 9Percent of Change

Percent of Change: The ratio of the amount of increase or decrease to the original amount

It is an increase when the new amount is larger than the original and a decrease when the new amount is smaller than the original.

To find the percent of change, use the following proportion:

Percent of change: Amount of increase or decrease = % Original Amount  100

Find the percent of change (be sure to label your answer as an increase or decrease).

Examples:Original amount: 20  Original amount: 40New amount: 30  New amount: 10 Percent of change=   Percent of change=

Example

A CD's original price was $12.99. It is now on sale for $10.99.What is the percent of change?

Example

A student's first test grade was 60. The second test grade was an 85.What was the percent of change?

Try this!

1. Original: 45 25% increase

What is the increase?What is the new amount?

2. Original: 100 45% decrease What is the decrease? What is the new amount?

In 2005, the price of a McDonald's hamburger was $0.89. In 2010, the price of a McDonald's hamburger was $1.19. What was the percent of change?

Original Amount: 52 New: 17 Find the percent of change.

Original Amount: 500 New: 700 Find the percent of change.

The number of students who attended FHS in 2010 was 1405. In 2011, 1380 students attended FHS. What was the percent of change in student enrollment?