Question

In: Statistics and Probability

Suppose the lifetime of a certain model of car battery is assumed to follow an exponential...

Suppose the lifetime of a certain model of car battery is assumed
to follow an exponential distribution with a mean lifetime of 5
years.
a. What is the probability that the total lifetime of the
5 batteries will exceed 9.85 years?
b. How many car batteries would be needed to be 90% sure that
the total lifetime would exceed 25 years? c. For a sample of size n = 5, put into service at the same time
1) What is the probability the first failure occurs before
2 years?
2) What is the probability the time between the first and
second failure is less than 2 years?
3) What is the expected time of the last failure?

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