please answer with correct and detailed calculations and explanations. make sure supporting statements are also provided for each step and calculation.

Problem 20-20 (Algo) Daily demand for a product is 170 units, with a standard deviation of 30 units. The review period is 20 days and the lead time is 6 days. At the time of review, there are 40 units in stock. If 90 percent service probability is desired, how many units should be ordered? Note: Use Excel's NORMSINV() 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. Order quantity units