A website manager has noticed that during the evening hours, about 1.5 people per minute check out from their shopping cart and make an online purchase. She believes that each purchase is independent of the others and wants to model the time between purchases. Complete parts a through c. a) What model would you use to model the time between events? O Geometric O Binomial O Normal O Exponential b) What is the mean time between purchases? The mean time between purchases is minutes. (Round to four decimal places as needed.) c) What is the probability that the time to the next purchase will be between 1 and 2 minutes? P(1 SXs 2) = (Round to four decimal places as needed.)