Benson Computer Services, Inc. has been in business for six months. The following are basic operating data for that period: Month Service hours July 110 Revenue $5,720 Operating costs $4,290 Aug- 140 $7,280 $5,300 Sept. Oct. Nov. Dec. 260 $13,520 $ 7,160 426 $22,152 $11,180 314 324 $16,328 $ 9,120 $16,848 $10,570 Required a. What is the average service revenue per hour in each month and the overall average for the six-month period? b. Use the high-low method to estimate the total monthly fixed cost and the variable cost per hour. c. Determine the average contribution margin per hour.