6.60 Show that the failure-rate function is given by Z(t) = t1, t>0, if and only if the time to failure distribution is the Weibull

6.60 Show that the failure-rate function is given by Z(t) = αβtβ−1, t>0, if and only if the time to failure distribution is the Weibull distribution f(t) = αβtβ−1 e

−αtβ

, t>0.