Proble Total Electricity Costs $2.500 3,000 3,600 4.500 3,200 4,900 4.100 3.800 5,100 4,200 3,300 6,100 Instructions a. Determine the fixed- and variable cost components using regression analysis (We recommend the use of Excel.) b. Prepare a scatter plot using Excel. Present the cost equation line estimated in part (a). c. What electricity cost does the cost equation estimate for a level of activity of 500 machine hours? By what amount does this differ from March's observed cost for 500 machine hours? January February March April May June July August September October November December Total Machine Hours 300 350 500 690 400 700 650 520 680 630 350 720