Ten 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%; 1980 hours
C) 20%; 1760 hours
D) cannot calculate from information provided
E) 80%; 920 hours

Question

Quizplus · Accepted Answer

FR(%) or Failure Rate is calculated as the number of failed units divided by the total number of units, which is 2 failed out of 10, resulting in a 20% failure rate. MTBF (Mean Time Between Failures) is calculated by dividing the total operational time by the number of failures. Here, 8 batteries lasted 200 hours (1600 hours), one lasted 20 hours, and another 140 hours, totaling 1760 hours. Dividing this by the number of failures (2) gives an MTBF of 880 hours.

Ten High-Technology Batteries Are Tested for 200 Hours Each