The controller of Wildhorse Production has collected the following monthly expense data for analyzing the cost behavior of electricity costs. January February March April May June July August September October November December Total Total Electricity Costs Machine Hours $2,450 230 3,060 380 3,520 480 4,760 685 3,190 410 4,910 800 4,030 650 3,870 5,040 680 4,260 3,250 6,580 820 540 610 380 (a) Determine the fixed- and variable-cost components using the high-low method. Fixed-costs Variable costs (b) What electricity cost does the cost equation estimate for a level of activity of 480 machine hours? Electricity costs By what amount does this differ from March's observed cost for 480 machine hours? Amount differs What electricity cost does the cost equation estimate for a level of activity of 780 machine hours? Electricity costs By what amount does this differ from June's observed cost for 780 machine hours? Amount differs