The controller of Sandhill Industries has collected the following monthly cost data for use in analyzing the behavior of maintenance costs. Total Maintenance Costs Total Machine Hours Month January $ 2,880 350 February 3,180 400 March 3.780 550 April 4,680 640 May 3,380 550 June 5,080 750 (a 1) 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 $