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) Hours of Activity Maintenance Costs January February 630 $ 4,300 380 3,100 March April May 500 3,700 350 2,920 600 4,450 June 390 3,060 July 380 3,130 August 620 4,570 September 590 4,360 October 570 4,150 November 440 3,400 December 420 3,260 Sum 5,880 $ 44,400 Average 490 3,700 A coefficient 896.74 B coefficient 5.7209 Standard error of the a coefficient Standard error of the b coefficient Standard error of the estimate 126.240 0.25205 90.528 R2 T-value a 0.98096 7.104 T-value b 22.697 What is the variable cost per hour using the high-low method to estimate the cost equation?