What percent of maximum life is achieved if the average life is 875 hours and the maximum is 1000 hours?

• A. 87.5 percent
• B. 85 percent
• C. 90 percent
• D. 80 percent

Answer: (A)

Percent of maximum life is found by comparing the observed value to the maximum: divide the observed life by the maximum life, then multiply by 100. Here, 875 hours divided by 1000 hours equals 0.875. Multiply by 100 to get 87.5 percent. So the average life is 87.5% of the maximum life. For context, 875 is 125 hours short of the maximum, which is 12.5% of 1000 hours, leaving 87.5% remaining. If it were 850, that would be 85%; 900 would be 90%; 800 would be 80%.