must use excel & show formulas #5

5) Weekly demand for a particular product averages 120 units, with a standard deviation of 6. This item is managed with a fixed-order-interval model. The order Interval is 5 weeks and has a certain lead time of one week. The desired service level is 98 percent. Assume it is now time to place an order, and there are 23 units on hand. How many units should be ordered? (10 pts)