A set of n = 30 components arc tested and their average lifetime is = 132.4

Question:

A set of n = 30 components arc tested and their average lifetime is = 132.4 hours.
(a) If the lifetimes are modeled with an exponential distribution, construct a 99% confidence interval for the mean time to failure.
(b) The components are advertised as having "an average lifetime of at least 150 hours." Do you think that this is a plausible claim?