I got A - D right but I can't figure out E. Can someone help?

PA 11-2 Anvil's Works requires on average... Anvil's Works requires on average 3000 tons of aluminum each week with a standard deviation of 1200 tons. The lead time to receive their orders is 10 weeks The holding cost for 1 ton of aluminum for one week is $12 They operate with a 99% in-stock probability. Use Table 115 (Round your answer to nearest Integer) a. On average how many tons do they have on order? 30,000 tons (Round your answer to nearest integer.) b. On average how many tons do they have on hand? (Refer above Table 11.5). 9,273 tons Round your answer to nearest integer) If their average inventory were 14500 tons, what would be their average holding cost per week? $ 174,000 per week (Round your answer to 2 decimal places) d. If their average Inventory were 12000 units what would be their average holding cost per ton of aluminum demanded each week? s 48.00 per ton (Round your answer to 3 decimal places) Suppose their on-hand inventory is 5000 tons on average. What in-stock probabrty do e they offer to their customers? Hint: Use the Excel function=NORM.S,DIST2. TRUE) Carry al least 3 decimals in your z value