The waiting time for a certain download to start is exponentially distributed with ? = 1.5 seconds. Let X be the time until the download begins, then X ? Exp(1.5).
(a) Give the expected value and variance.
(b) What does the expected value represent?
(c) What is the probability that the download will start before 5 seconds have passed?
(d) What is the probability that it takes at least 3 seconds for the download to start?
(e) What is the median time (50th percentile) for a download to start?
hint: find the value of x that solves F(x) = 0.50.