a. Determine which delivery alternative would be most economical for 80 boxes of parts. Each box costs $200 and annual holding cost is 30 percent of cost. Assume 365 days per year. Freight costs are:

Alternative                                     Freight Cost (for all 80 boxes)

Overnight .....................................................     $300

Two-day ........................................................      260

Six-day ..........................................................      180

b. For what range of unit cost for a box would each delivery alternative be least costly?