A Duane model reliability growth test was run, and resulted failures at the following times: 20, 60, 110, 170, 250 and 350 hours.
a) What is the growth rate (β)?
b) What is the cumulative MTBF (MTBFc) at the end of the test (350 hours)? Use the value given by the fitted line, not the data point itself.
c) What is the instantaneous MTBF (MTBFi) at the end of the test (350 hours)?
d) If the test is extended to 500 hours (total, not restarted), and the same growth rate continues, what would the instantaneous MTBF (MTBFi) be at 500 hours?