Number of Cars at a Tollgate During a certain part of the day, an average of
five automobiles arrives every minute at the tollgate on a turnpike. Let \(X\)
be the number of automobiles that arrive in any 1 -minute interval selected at
random. Let \(Y\) be the interarrival time between any two successive arrivals.
(The average interarrival time is \(\frac{1}{5}\) minute.) Assume that \(X\) is a
Poisson random variable and that \(Y\) is an exponential random variable.
(a) Find the probability that at least five cars arrive during a given
1-minute interval.
(b) Find the probability that the time between any two successive cars is less
than \(\frac{1}{5}\) minute.