21. Niketa is the manager of the student center cafeteria. She is introducing pizza as a menu item. The pizza is ordered frozen from a local pizza establishment and baked at the cafeteria. Niketa anticipates a weekly demand of 10 pizzas. The cafeteria is open 45 weeks a year, 5 days a week. The ordering cost is $15 and the holding cost is $0.40 per pizza per year. What is the optimal number of pizzas Niketa should order?
22. Christina sells beauty supplies. Her annual demand for a particular skin lotion is 1,000 units. The cost of placing an order is $20, while the holding cost per unit per year is 10 percent of the cost. This item currently costs $10 if the order quantity is less than 300. For orders of 300 units or more, the cost falls to $9.80. To minimize total cost, how many units should Christina order each time she places an order?
23. Suppose that Frank's lead-time demand is normally distributed with a mean of 100 units and a standard deviation of 20 units. If Frank wants to maintain a 97% service level, what should the reorder point be?
24. What are some of the assumptions made in using EOQ?
25. When using safety stock, how is the standard deviation of demand during the lead time calculated if the daily demand is normally distributed but the lead time is constant? How is it calculated if daily demand is constant but lead time is normally distributed? How is it calculated if both daily demand and lead time are normally distributed?