A system consists of five components is connected in series as shown below.

As soon as one component fails, the entire system will fail. Assume that the components fail independently of one another.

(a)Suppose that each of the first two components have lifetimes that are exponentially distributed with mean 100 weeks, and that each of the last three components have lifetimes that are exponentially distributed with mean 124 weeks. Find the probability that the system lasts at least 60 weeks.

(b)Now suppose that each component has a lifetime that is exponentially distributed with the same mean. What must that mean be (in years) so that 99% of all such systems lasts at least one year?