The inverse power rule model is sometimes used in

accelerated stress testing. The model is defined by

where C and m are constants and v s = voltage at a high

stress level. Reliability decreases proportional to the inverse of a power of

the stress. Given the following test data, estimate the MTTF at a normal stress

level of 90 volts. Assuming a CFR, what is the one-year (24 hr/day)

reliability?