Walton Computer Services, Inc. has been in business for six months. The following are basic operating data for that period: Month July Aug. Oct. Sept. Nov. Dec. 428 Service hours 316 330 110 132 260 $6,380 $4,280 $7,656 $5,300 $18,328 $ 9,170 $15,080 $ 7,190 $24,824 $11,150 $19,140 $10,570 Revenue Operating costs 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