4. (Problem 9) Custom Computers, Inc. assembles custom home computer systems. The heat sinks needed are bought for $12 each and are ordered in quantities of 1,300 units. Annual demand is 5,200 heat sinks, the annual inventory holding cost rate is $3 per unit, and the cost to place an order is estimated to be $50. Calculate the following: a) Average inventory level b) The number of orders placed per year c) The total annual inventory holding cost d) The total annual ordering cost e) The total annual cost