The number of years a radio functions is exponentially distr

The number of years a radio functions is exponentially distributed with parameter lambda = 1/8. If Jones buys a used radio, what is the probability that it will be working after an additional 8 years?

Solution

X - No of years a radio functions

X is exponential with lemda = 1/8

Prob that it will be working after an additional 8 years

= P(X>8)

= 1-P(X<8)

= 1-e^-8/8

= 0.6321