The following information is available for electricity costs for the first six months of the year:

Month	Production Volume	Electricity Cost
January	4,200	$48,000
February	1,500	24,000
March	1,100	16,000
April	2,900	32,000
May	5,100	52,000
June	2,200	32,000

Using the high-low method, an estimate of the variable cost per unit of production would be