Westminster Company has had the following experience over the past five quarters: Units produced Electricity cost ($) 27,000 101,000 32,000 120,000 31,000 116,000 20,000 84,000 22,000 90,000 a) Using the high-low method, determine an equation for electricity cost (Y) as a function of units produced (X). Assume a linear function. b) Using your equation, forecast electricity cost at a volume of 30,000 units produced.