One of Super Giant’s grocery stores in Pennsylvania sells, on average, 1,120 cases of Pepsi products a week with a standard deviation of 146 cases. Josh Nelson, who is the Pepsi account manager for this store, receives a bonus if the store’s weekly sales over a four week period during the month average more than 1,200 cases.

a. What is the probability that Josh will receive a bonus next month?

b. What assumptions are needed to answer part a?