Probability with R, 2nd Edition

16The Exponential Distribution

16.1 Modeling Waiting Times

Example 16.1

You have observed that the number of hits to your website follow a Poisson distribution at a rate of 2 per day on average.

Let be the time (in days) between hits.

(the waiting time between hits is less than one day)

(two days will elapse without a hit)

(the time between hits is between one and two days)

Example 16.2

You observe the number of telephone calls that arrive each day on your phone over a period of a year, and note that the arrivals follow a Poisson distribution with an average of three per day.

Let be the waiting time between calls.

(you will be waiting less than half a day for a call)

(you will be waiting more than a day for a call)

(you will wait at least half a day and less than one day for a call)