Percent of Change to Calculate a New Amount

Percent of Change

Definitions

• Percent of Change - the percent by which a number increases or decreases.

• Percent Decrease - a percent change describing a decrease in a quantity.

• Percent Increase- The percent change describing an increase in a quantity.

What kind of Percent of Change

• Percent increase determines the rate of growth and the answer will be a positive percent.

• Percent decrease determines the rate of decline and the answer will be a negative percent.

• Both percent increase and percent decrease can be calculated using the ratio :

   $\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{quantity\ ofchange}{original\ quantity}$  

Multiple Choice

What is the percent of change? 55 mph to 70 mph

• 27% increase

• 27% decrease

• 21% increase

• 21% decrease

How did you do that?

•  $\frac{quantity\ of\ change}{original\ quantity}$  

•  $\frac{15}{55}\ =\ .27272727272727.....$  

• 27% increase

Multiple Choice

What is the percent of change? 92 lb to 200 lb

• 54% increase

• 54% decrease

• 117% increase

• 117% decrease

How did you do that?

•  $\frac{quantity\ of\ change}{original\ quantity}$  

•  $\frac{108}{92}\ =\ 1.1739.....$  

• 117% increase

Multiple Choice

What is the percent of change? 5 ft to 5 ½ ft

• 10% increase

• 10% decrease

• 9% increase

• 9% decrease

Multiple Choice

What is the percent of change? 70 mph to 55 mph

• 21% decrease

• 21% increase

• 27% increase

• 27% decrease

Multiple Choice

What is the percen of change? 18.7 kg to 4.5 kg

• 76% increase

• 76% decrease

• 3% increase

• 3% decrease

Multiple Choice

What is the percent of change? 4.72 million to 3.15 million

• 33% increase

• 33% decrease

• 50% increase

• 50% decrease