The next three questions all use the same data set. Using the high-low method and the data below, what is the variable cost per unit of volume for the maintenance costs? (Your answer should include a leading zero, decimal point, two decimal places, and no dollar sign. For example if your answer is .12, type your answer as 0.12.) Maintenance Month Volume Costs ($) July 3,000 2,500 August 4,000 3,000 September 7,000 4,600 October 9,000 5,500 November 5,000 3,200 December 10,000 6,000