A lab orders a number of chemicals from the same supplier, with a lead time two weeks. The assistant manager of the lab must determine how much of one of these chemicals to order. Usage of the chemical is appropriately normal, with a mean of 15 ml per week and a standard deviation of 5 ml. The lab management decides that the desired service level for this chemical is 95%. a) What is the average amount of safety stock of the chemical? b) How much chemical should he ordered?