Maximum life is 1200 hours; observed average life is 960 hours. What percent of maximum life has been achieved?

• A. 75 percent
• B. 85 percent
• C. 90 percent
• D. 80 percent

Answer: (D)

The idea being tested is how to express a value as a percent of a maximum. Take the observed life and compare it to the maximum: divide 960 by 1200, then convert to a percentage. 960 ÷ 1200 = 0.8, and 0.8 × 100 = 80%. So 80 percent of the maximum life has been achieved. For reference, 75 percent would be 900 hours, 85 percent would be 1020 hours, and 90 percent would be 1080 hours, which don’t match the observed 960 hours.