Assume that car batteries lifetimes follow an exponential distribution with mean 3 years.
(a) What is the probability that a battery lasts 10 years or more?
(b) In a group of ten batteries what is the probability that at least one will last 10
years or more?
(c) How many batteries do we need in order to have at least one last 10 years or
more with probability 0.9?
