The following growth model is a marvel in simplicity and

utility where A is the instantaneous failure rate and T is the cumulative test

time measured in 1000s of hours. The parameter a represents the external

failure mode rate (which cannot be influenced by design) and b is the internal

failure mode failure rate prior to growth testing (i.e., T = 0).

Given the following test data where A is an estimate for the

instantaneous failure rate for the current test cycle, find the least-square

estimates for a and b and determine how many total test hours will be required

to obtain a MTTF of 30,000 hr.