After 1 month of integration testing, 20 errors have been removed, the MTTF of the software is measured by testing it with the use of simulated operational data, and the MTTF = 10 hours. After 2 months, the MTTF = 20 hours, and 50 total errors have been removed.
(a) Assuming a constant error-removal rate, fit a model to this data set. Estimate the parameters by using moment-estimation techniques [Eqs. (5.47a, b)].
(b) Sketch the MTTF versus development time t.
(c) How much integration test time will be required to achieve a 60-hour MTTF? How many errors will have been removed by this time and how many will remain?
(d) If we release the software when it achieves a 60-hour MTTF, sketch the reliability function versus time.
(e) How long can the software operate, if released as in part (d) above, before the reliability drops to 0.90?