Please help solve a. What is the optimal target level (order-up-to level)? (Use Excel's NORMSINV() function to find the correct critical value for the given -level. Do not round intermediate calculations. Round "z" value to 2 decimal places and final answer to the nearest whole number.)

and

b. If the service probability requirement is 95 percent, the optimal target level will:

Thank you!

Problem 20-36 (Algo) Palin's Muffler Shop has one standard muffler that fits a large variety of cars. The shop wishes to establish a periodic review system to manage inventory of this standard muffler. Use the information in the following table to determine the optimal inventory target level (or order-up-to level). Annual demand Standard deviation of daily demand Item cost Annual holding cost Review period 2,400 mufflers 6 mufflers per working day $21.00 per muffler 36 % of item value 15 working days Ordering cost Service probability Lead time Working days $ 90 per order 81 % 3 working days 200 per year a. What is the optimal target level (order-up-to level? (Use Excel's NORMSINVO) function to find the correct critical value for the given a-level. Do not round intermediate calculations. Round "z' value to 2 decimal places and final answer to the nearest whole number.) Optimal target level b. If the service probability requirement is 95 percent, the optimal target level will: Increase Decrease Stay the same