Problem: UDI Pharmaceuticals orders its antibiotics every three weeks (21 days) when a salesperson visits from one of the Pharmaceutical companies. Tetracycline is one of its most prescribed antibiotics, with average daily demand of 2,000 capsules. The standard deviation of daily demand was derived from examining prescriptions filled over the past three months and was found to be 400 capsules. It takes four days for the order to arrive.
UDI uses Fixed - Time Period Model. UDI would like to satisfy 95 percent of the prescriptions. The salesperson just arrived, and there are currently 20,000 capsules in stock. How many capsules should be ordered?