Platinum Electric recently embarked on a massive training campaign to improve its operations. The average time to repair a failure on their main machine has improved by over 40%. On average, it now takes 5 hours to repair the company's key machine. Assume that repair time is exponentially distributed. Calculate the chance that the next repair duration will be between 3 hours and 7 hours. (8) A manufacturer of disk drives for notebook computers wants a MTBF of at least 50 000 hours. Recent test results for 10 units were one failure at 10 000 hours, another at 25 000 hours, and two more at 45 000 hours. The remaining units were still running at 60 000 hours. Determine the following: a) Percent of failures. (3) b) Number of failures per unit hour. c) MTBF at this point in the testing.