i need help with the first picture problems. its going to ask the second picture questions a-d

You are in charge of inventory control of a highly successful product retailed by your firm. Weekly demand for this item varies, with an average of 150 units and a standard deviation of 15 units. It is purchased from a wholesaler at a cost of $15.00 per unit. The supply lead time is 8 weeks. Placing an order costs $52.00, and the inventory carrying rate per year is 15 percent of the iter's cost. Your firm operates 6 days per week, 48 weeks per year. Refer to the standard nomal table for z-values. a. What is the optimal ordering quantity for this item? units. (Enter your response rounded to the nearest wholo number.) You are in charge of inventory control of a highly successful product retailed by your firm, Weekly demand for this item varies, with an average of 350 unts and a standard deviation of 24 units. It is purchased from a wholesaler at a cost of $15.00 per unit. The supply lead time is 7 weeks. Placing an order costs S60.00, and the inventory carrying rate per year is 25 percent of the item's cost. Your firm operates 5 days per week, 51 weeks per year. Refer to the standard normal table for z-values. a. What is the optimal ordering quantity for this item? units. (Enter your rosponse rounded to the nearest whole number.) b. How many units of the item should be maintained as safety stock for 92 percent protection against stockouts during an order cycle? 90 units. (Enter your response rounded to the nearest whole number.) c. If supply lead time can be reduced to 4 weeks, what is the percent reduction in the number of units maintained as safety stock for the same 92 percent stockout protection? 24.44%. (Enter your response rounded to two decimal places.) d. If through appropriate sales promotions, the demand variability is reduced so that the standard deviation of weekly demand is 12 units instead of 24 , what is the percent reduction (compared to that in part (b)) in the number of units maintained as safety stock for the same 92 percent stockout protection? 50.00%. (Enter your rosponse rounded to fwo decimal places.)