The following information is available for electricity costs for the last six months of the year: Month Production Volume Electricity Costs February 1,000 $1,700 March 2,200 4,000 April 2,000 3,200 May 1,630 3,100 June 1,240 2,600 July 1,340 3,020 Using the high-low method, what is the estimated variable cost per unit of production? (Round your answer to two decimal places.) a.1.92 b.1.37 c.1.75 d.1.53