A website manager has noticed that during the evening hours, about 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 number of purchases per minute. a) What model might you suggest to model the number of purchases per minute? b) What is the probability that in any one minute at least one purchase is made? c) What is the probability that seven people make a purchase in the next four minutes?