Wilkens Company wants to determine the cost behavior pattern of maintenance costs. Wilkens has decided to use linear regression by employing the equation y = a + bx for maintenance costs. The prior year's data regarding maintenance hours and costs, and the results of the regression analysis are given in the data below. Hours of Activity Maintenance Costs January 480 4,200 February 320 3,000 March 400 3,600 April 300 2,820 May 500 4,350 June 310 2,960 July 320 3,030 August 520 4,470 September 490 4,260 October 470 4,050 November 350 3,300 December 340 3,160 Total 4,800 $43,200 Average 400 $ 3,600 Average cost per hour $9.00 A 684.65 b 7.2884 Standard error of a 49.515 Standard error of b 0.12126 Standard error of the estimate 34.469 r 0.99724 "R-SQUARED" 0.99448 a. Refer to the Wilkens Company. Based upon the data derived from the regression analysis, what maintenance costs should be budgeted for a month in which 420 maintenance hours will be worked? b. Refer to the Wilkens Company. What is the percentage of the total variance that can be explained by the regression equation