Av city (problem 13.1) assumed with certainty that the order- ing cost is $625/order and the inventory carrying cost is $130/unit/ year. however, the inventory model parameters are frequently only estimates that are subject to some degree of uncertainty. consider four cases of variation in the model parameters as follows: (a) both ordering cost and carrying cost are 10% less than originally estim- ated; (b) both ordering cost and carrying cost are 10% higher than lus a few sundays, or approximately 320 days per year. determine the following: a. optimal order quantity per order b. total annual inventory costs c. optimal number of orders to place per year d. number of operating days between orders, based on the optimal orderin