Information about Indiana Industrial's utility cost for the last six months of 2010 follows. The highlow method will be used to develop a cost formula

Information about Indiana Industrial's utility cost for the last six months of 2010 follows. The high–low method will be used to develop a cost formula to predict 2011 utility charges, and the number of machine hours has been found to be an appropriate cost driver. Data for the first half of 2010 are not being considered because the utility company imposed a significant rate change as of July 1, 2010.

a. What is the cost formula for utility expense?
b. What is the budgeted utility cost for September 2011 if 31,250 machine hours areprojected?

Machine Hous Utility Cost Month July August September October November December 33,750 34,000 33,150 32,000 31,250 31,000 $13000 12,200 11,040 11,960 11,500 11,720