4. A manufacturer of computer workstations gathered average monthly sales figures from its 56 branch offices and dealerships across the country and estimated the following demand for its product: O = +15,000 - 2.80P + 150A + 0.3Ppe + 0.35Pm + 0.2Pc (5,234) (1.29) (175) (0.12) (0.17) (0.13) R2 = 0.68 SEE = 786 F = 21.25 The variables and their assumed values are Q = Quantity P = Price of basic model = 7,000 A = Advertising expenditures (in thousands) = 52 Ppc = Average price of a personal computer = 4,000 Pm = Average price of a minicomputer = 15,000 Po = Average price of a leading competitor's workstation = 8,000