Web visitors, part 2. The website manager in Exercise 49 wants to model the time between purchases. Recall that the mean number of purchases in the evening is 3 per minute.
a) What model would you use to model the time between events?
b) What is the mean time between purchases?
c) What is the probability that the time to the next purchase will be between 1 and 2 minutes?
Exercise 49
Quality control. In an effort to improve the quality of their cell phones, a manufacturing manager records the number of faulty phones in each day's production run. The manager notices that the number of faulty cell phones in a production run of cell phones is usually small and that the quality of one day's run seems to have no bearing on the next day.
a) What model might you use to model the number of faulty cell phones produced in one day?
b) If the mean number of faulty cell phones is 2 per day, what is the probability that no faulty cell phones will be produced tomorrow?
c) If the mean number of faulty cell phones is 2 per day, what is the probability that 3 or more faulty cell phones were produced in today's run?