In an inventory study it was determined that on average demands for a particular item at a warehouse were made four times per day. What is the probability that on a given day an item is requested
(a) More than four times?
(b) Not at all?
(c) If only 4 items are stocked, what is the probability of not having enough on a given day?
(d) How many items would need to be stocked if the probability of not having enough on a given day is 5%?