Gargymal Company would like to estimate the variable and fixed components of its electrical costs and has compiled the following data for the last five months of operations.

	Machine Hours	Electrical Cost
August	1,000	$1,550
September	900	1,510
October	1,500	1,750
November	2,000	1,950
December	1,300	1,670

Using the high-low method of analysis, the estimated variable cost per machine hour for electricity is closest to?