Consider a periodic review system. Demand averages 240 units per day. Orders are placed every 10 days. The firm strives to provide a 96 % cycle service level. a) How many units of safety stock should be held? b) What should the order up to level be? c) Suppose that it is time to review the item. There are 150 units in inventory. An order for 200 units is on the way, and there is an outstanding back order for 500 units. How many units should be ordered?