Nationwide auto parts uses a periodic review inventory control system for one of its stock items. the review interval is 4 weeks, and the lead time for receiving the materials ordered from its wholesaler is 1 weeks. weekly demand is normally distributed, with a mean of 150 units and a standard deviation of 30 units. refer to the standard normal table for z-values. a. what is the average and the standard deviation of demand during the protection interval? the average demand during the protection interval is nothing units. (enter your response as an integer.)