Customers arrive at a checkout counter at a department store an average of 8 times per hour. Twenty percent of them are buying things from section A of the store. a) Find the probability of getting fewer than seven customers at the checkout counter in one hour. How are supposed to know? There is a table in the back of the book that we can use to look stuff up, but I don't really understand it. I am not even sure if that's what I need, but this question seems impossible. b) Find the probability of getting fewer than seven customers at checkout counter for seven of the next 10 hours. Still have no idea c) Find the probability of having at least seven customers arrive at the checkout counter before a customer buying things from section A arrives at the checkout counter. Seems possible...negative binomial distribution? d) From 80 purchases made at the checkout counter, suppose that 21 were from section A. An auditor samples 10 purchases, find the probability that 5 of them are from section A. Hypergeometric?