申論題

3. (15 points in total) A wire-spinning machine will spin, on average, 12.3 miles before needing maintenance. Assume the time between maintenance is exponentially distributed.

(3) You are the Webmaster for your firm's Website. From your records, you know that the probability that a visitor will buy something from your firm is 0.23. If the number of visitors in one day is 952, what is the probability that less than 200 of them will buy something from your firm? Use the normal approximation for the binomial. (5 points)