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 500 $ 4,220 february 330 3,020 march 420 3,620 april 310 2,840 may 520 4,370 june 320 2,980 july 330 3,050 august 540 4,490 september 510 4,280 october 490 4,070 november 360 3,320 december 350 3,180 sum 4,980 $ 43,440 average 415 3,620 a coefficient 760.50 b coefficient 6.8904 standard error of the a coefficient 57.854 standard error of the b coefficient 0.13646 standard error of the estimate 41.006 r2 0.99609 t-value a 13.145 t-value b 50.494 what is the variable cost per hour using the high-low method to estimate the cost equation? multiple choice $8.60 $7.17 $0.1274 $0.1062