The controller of Sheridan Industries has collected the following monthly cost data for use in analyzing the behavior of maintenance costs. Month Total Maintenance Costs Total Machine Hours January $2,735 3,620 February 3,108 4,144 March 3,730 6,216 April 4,662 8,184 May 3.315 5,180 June 4,832 8,280 (a1) Determine the unit variable costs using the high-low method for this mixed cost. (Round answer to 2 decimal places e.g. 2.25.) Variable cost per machine hour $