Suppose that units are placed on test and that three of them fail at 150, 300, and

Question:

Suppose that units are placed on test and that three of them fail at 150, 300, and 500 hours, respectively. The test is terminated at 2,000 hours, and no failed units are replaced during the test. Estimate the MTTF and the reliability of these units at 5,000 hours. Assuming that the lifetime has an exponential distribution, find 95% confidence interval on these quantities.