Practice!

Sample Problem

Sasha could run one mile in 10 minutes last year. She can run a mile in 8 minutes this year. By what percent did her timing improve?

%

Solution

Use the formula:

Percent Change = amount of change/original amount × 100%

Percent Decrease= (amount of decrease)/original amount × 100%

The amount of change: (10 – 8) minutes

The original amount: 10 minutes

Thus, percent change: (10 – 8) ÷ 10 = 0.20 = 20%