Unless stated otherwise in the exercise, use software to find the exact Poisson.

Question 5.52

5.52 Website hits.

A “hit” for a website is a request for a file from the website’s server computer. Some popular websites have thousands of hits per minute. One popular website boasts an average of 6500 hits per minute between the hours of 9 A.M. and 6 P.M. Assume that the hits per hour are well modeled by the Poisson distribution. Some software packages will have trouble calculating Poisson probabilities with such a large value of .

  1. Use Excel’s Poisson function to calculate the probability of 6400 or more hits during the minute beginning at 10:05 A.M. What did you get?
  2. Find the probability of part (a) using the Normal approximation.
  3. Minitab users only: Try calculating the probability of part (a) using the Minitab’s Poisson option. Did you get an answer? If not, how did the software respond? What is the largest value of that Minitab can handle?