You work in a store. On average, you see that 3 customers come to the store every hour. Calculate the following: a) What is the probability that at least 2 and as many as 4 customers come to the store in a given hour? b) The mean rate of customer decreases to 5 customers every 2 hours. During one hour, what is the most likely number of customers that will come to the store (hint: the answer must be an integer)?