The following information is available for a company's utility cost for operating its machines over the last four months. Month January February March Machine hours 990 1,890 2,580 690 Utility cost $5,540 $7,080 $8,100 $3,330 April Using the high-low method, the estimated variable cost per machine hour for utilities is: Multiple Choice $4.83 O $3.14. O $3.91. $2.52. O O $7.37