You test 10 components for 60 hours. Failures were recorded at the following times (units are in hours) 0.1 2, 3, 4

a) Give the estimated and MTTF.

b) Suppose you need to be 95% confident that the true failure rate is < 0.99 hours-1. What is the maximum failure rate you could have estimated in part a), assuming that there were four failures?

c) For planning this experiment. What is the maximum number of failures that would be allowable, given that you want to be 95% confident that the true failure rate is <0.99 hours-1?