Month Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Maintenance Machine Cost Hours $ 4,550 620 3,350 460 3,950 540 3,170 440 4,700 640 3,310 450 3,380 460 4,820 680 4,610 630 4,400 610 3,650 490 3,510 480 $47,400 6,500 Sum Average $ 3,950 Average cost per hour a (intercept) b (coefficient) Standard error of the estimate R-squared t-value for b $ 542 $ 7.00 $ 129.77 7.0527 52.8466 0.9935 39.130 Based on the data derived from the regression analysis, 420 maintenance hours in a month mean that maintenance costs should be budgeted to the nearest dollar at