Machine hours and electricity costs for AMK industries for the past eleven months were as follows: Month Machine Hours Electricity costs January 2,000 $18.900 February 2,400 21,500 March 1,400 14,000 April 2,600 23,500 May 3,300 28,750 June 3,300 22.700 July 3,600 25,250 August 3,000 23,250 September 1,500 16,000 October 3,300 26,500 November 4,200 31.500 Required: a. Using the high-low method, develop an estimate of variable electricity costs per machine hour. b. Using the high-low method, develop an estimate of fixed electricity costs per month. c. Using the high-low method, develop a cost function for monthly electricity costs. d. Estimate electricity costs for a month in which 1,300 machine hours are worked