The McGraw Company is accumulating data to be used in preparing its annual profit plan for the coming year. The cost behavior pattern of the maintenance costs must be determined. The accounting staff has suggested that linear regression be employed to derive an equation in the form of y = a + bx for maintenance costs. Data regarding the maintenance hours and costs for last year and the results of the regression analysis are as follows: (CMA adapted) January February March April Hours of Activity 640 400 520 360 630 May June July August September October November December Sum Average 410 400 660 610 590 460 440 6, 120 510 Maintenance Costs $ 4,320 3, 120 3,720 2.940 4, 470 3,880 3, 150 4,590 4.380 4. 170 3, 420 3,280 $ 44, 640 3, 720 510 3,720 Sum Average 851.25 5.6250 A coefficient B coefficient Standard error of the a coefficient 101.960 Standard error of the b coefficient 0.19575 Standard error of the estimate R T-value a T-value 71.764 0.98803 8.349 28.735 2