Twenty high-technology batteries are tested for 200 hours each. One failed at 20 hours; another failed at 140 hours; all others completed the test. FR(%) is ________ and MTBF is ________.
A) 20%; 880 hours
B) 10%; 3760 hours
C) 20%; 3760 hours
D) 10%; 1880 hours
E) 80%; 920 hours

Question

Quizplus · Accepted Answer

FR(%) = (number of failures/total number of batteries tested) * 100% 
FR(%) = (2/20) * 100% 
FR(%) = 10%

MTBF = (total test time/number of batteries that failed) 
MTBF = [(20+140+180*18)/2] hours 
MTBF = 1880 hours

Twenty High-Technology Batteries Are Tested for 200 Hours Each