(Best Buy Part B) At a Best Buy store, the annual demand of a headphone is 15600. It costs $400 to place an order, the holding cost for a headphone is 10% of the unit cost, and the manufacturer chanrges $50 for each headphone. The unit time is one week and the manufacturer takes 2 weeks to supply an order. The store manager finds that the weekly demand is random, and normally distributed with a standard deviation of 200.