Question

Suppose that a market research analyst for a cell phone company conducts a study of their customers
who exceeds the time allowance included on their basic cell phone contract. The analyst finds that for
those people who exceed the time included in their basic contract, the excess time used follows an
exponential distribution with a mean of 22 minutes. Consider a random sample of 80 customers who
exceed the time allowance included in their basic cell phone contract.
a) Find the probability that the mean excess time used by the 80 customers in the sample is longer
than 20 minutes.

Answer 1

I didn't understood the question clearly.....