Simple Linear Regression Method undependent Dependent variable Variable activity mixed cost X y xy x 2 50 250 25 10 70 700 100 20 180 2400 400 15 100 1500 225 X 110 1650 225 10 30 80 800 100 150 4500 900 25 130 3250 625 20 O' 115 2300 400 80 800 100 15 100 225 50 1500 200 10000 2500 Ex= 225 Ey= 1305 Exy = 29650 {x2 5825 Normal equations Sxy = aEx + 65 x2 ( 1) where: a = fixed costs zy =na + 68x (2) b=unit variable costs