A test score increases from 72 to 84. What is the percent increase (to one decimal place)?

• A. 16.7%
• B. 14%
• C. 16%
• D. 18%

Answer: (A)

When a score goes up, the percent increase is the amount of the increase divided by the original score, times 100. The increase is 84 − 72 = 12. So the percent increase is (12 / 72) × 100 = 16.666...%, which rounds to 16.7% to one decimal place.

This makes sense because 16.7% of 72 is about 12, and 72 plus that 16.7% gives you 84. The other options correspond to different percentages of 72 (for example, 16% of 72 would be 11.52, giving 83.52; 18% would be 12.96, giving 84.96), which don’t result in 84.