also answer: b) number of failures per unit hour = c) the mean time between failures? MTBF is the expected time between a repair and the next failure of a component, machine, process, or product. MTBF is the reciprocal of FR(N): MTBF at this time in testing. round to nearest whole number

A manufacturer of disk drives for notebook computers wants a MTBF of at least 50,000 hours. Recent test results for 12 units were one failure at 10,000 hours, two at 25,000 hours, and two more at 40,000 hours. The remaining units were still running at 60,000 hours. Determine the following: a) Percent of failures =% (enter your response as a percentage rounded to one decimal place)