only part a

Suppose that two electronic components in the guidance system for a missile operate independently and that each has a length of life governed by the exponential distribution with mean 7 (with measurements in hundreds of hours). (a) Find the probability density function for the average length of life of the two components. _ E 19 (7) , uz 0 . fu(u)= 7 x v 0 , elsewhere I (b) Find the mean and variance of this average, using the answer in part (a) Check your answer by computing the mean and variance, using this theorem. mean 7 'I variance 24.5 v