Suppose that a company offers quantity discounts. If up to 1000 units are purchased, the unit price is $ 10; if more than 1000 and up to 5000 units are purchased, the unit price is $ 9; and if more than 5000 units are purchased, the unit price is $ 7.50. Develop a spreadsheet using the VLOOKUP function to find the unit price associated with any order quantity and compute the total cost of the order.