Armer Company is accumulating data to use 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 the use of linear regression to derive an equation for maintenance hours and costs. Data regarding the maintenance hours and costs for the last year and the results of the regression analysis follow: Maintenance Month Cost Jan. $ 4,200 Feb. 3,000 Mar. 3,600 Apr. 2,820 May 4,350 June 2,960 July 3,030 Aug. 4,470 Sept. 4,260 Oct. 4,050 Nov. 3,300 Dec. 3,160 Sum $43,200 Average $ 3,600 Average cost per hour a (intercept) b (coefficient) Standard error of the estimate R-squared t-value for b Machine Hours 480 320 400 300 500 310 320 520 490 470 350 340 4,800 $ 400 $ 9.00 $ 684.65 7.2884 34.469 0.99724 60.105 If Armer Company uses the high-low method of analysis, the equation for the relationship between hours of activity and maintenance cost follows: y = 400 + 9.0x y= 570 + 7.5x y= 3,600 + 400x y=570 + 9.0x None of these answer choices are correct