Sympco Glass manufactures insulated windows. The firms repair and maintenance (R&M) cost is mixed and varies most directly with machine hours worked. The following data have been gathered from recent operations:

Month	MHs	R&M Cost
May	1,410	$ 9,739
June	1,900	11,735
July	2,020	12,059
August	2,520	14,462
September	2,250	12,993
October	2,690	14,667
November	1,680	10,341
December	2,300	12,945

a. Use the highlow method to estimate a cost formula for repairs and maintenance. Round your answer for variable cost to the nearest cent. Use this rounded variable cost amount to calculate the fixed cost, and then round your answer for fixed cost to the nearest dollar. Total R&M cost = $ + $ MH

b. Use least squares regression to estimate a cost formula for repairs and maintenance. You must use the least-squares formula provided in the chapter appendix to calculate the variable and fixed costs. Round your answers for b (the variable cost) and for a (the fixed cost) to the nearest cent. When solving the equation for a, round the value of b, y-bar, and x-bar to two decimal places. Total R&M cost = $ + $ MH

c. Does the answer to (a) or to (b) provide the better estimate of the relationship between repairs and maintenance costs and machine hours?