Calculate the mean life and availability associated with the 26 airplanes sampled. Of the 13 failures, one occurred at 60,000 hrs, the second at 74,000 hrs, and the remainder at 50,000 hrs. The rest of the airplanes showed no signs of failures when the test was terminated at 75,000 hrs. The average time to inspect and/or repair any of the planes was 15 hours.