The management of Buff Sports Stadium believes that the number of sporting events each month is an measure of activity for total clean-up cost. Shown below are event figures and total clean up costs for the past four months:

Month Number of sporting events Total clean up cost

july 28 $30,900

august 34 $34,200

sept 16 $20,700

oct 22 $28,200

Required: a. Estimate Buff's cost formula for monthly clean-up cost using the high-low method.

b. Estimate Buff's cost formula for monthly clean-up cost using the least-squares regression method.