The controller of Cullumber Production has collected the following monthly expense data for analyzing the cost behavior of electricity costs. Determine the fixed- and variable-cost components using the high-low method. Fixed-costs Variable cost per machine hour Question Part Score 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 differ $ 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 differ $