please explain without excel

15) The daily demand for a product is normally distributed with a mean of 80 and a standard deviation of 8. Constant lead time is 4 days. The cost of placing an order is $20. The item costs $8 and the carrying rate per year is 10% of the item cost. Determine the reorder point to satisfy 90% of the orders. 16) A manager has just received a revised price schedule from a vendor. What order quantity should the manager use in order to minimize total costs? Annual demand is 120 units, ordering cost is $10, and annual carrying cost is S1 per unit. Quantity Unit Price 1-59 160.99 S15 $14 S13 100 or more 17) A bakery's use of corn syrup is normally distributed with a mean of 50 gallons per day and a standard deviation of 5 gallons per day. Lead time for delivery of the syrup is normal with a mean of 4 days and a standard deviation of 2 days. The manager reorders when his inventory drops to 300 gallons. What cycle service level is implied by this policy