Davis Company's activity for the first six months of the current year is as follows: January February March April May June Machine Hours 2,000 3,000 2,400 1,900 1,800 2,100 Electrical Cost $1,560 2,200 1,750 1,520 1,480 1,600 Using the high-low method, what is the variable cost per machine hour? $0.40 per hour. $0.60 per hour. $0.64 per hour. $0.67 per hour