The McGraw Company is accumulating data to be used in preparing its annual profit plan for the coming year. The cost behavior pattern of the maintenance costs must be determined. The accounting staff has suggested that linear regression be employed to derive an equation in the form of y = a + bx for maintenance costs. Data regarding the maintenance hours and costs for last year and the results of the regression analysis are as follows: (CMA adapted)

	Hours of Activity				Maintenance Costs
January		540			$	4,420
February		500				3,220
March		630				3,820
April		460				3,040
May		780				4,570
June		510				3,180
July		500				3,250
August		810				4,690
September		760				4,480
October		730				4,270
November		560				3,520
December		540				3,380
Sum		7,320			$	45,840
Average		610				3,820
A coefficient						1,146.03
B coefficient						4.3836
Standard error of the a coefficient		454.871
Standard error of the b coefficient		0.73148
Standard error of the estimate						306.174
R2						0.78220
T-value a						2.519
T-value b						5.993

What would be the cost equation if the high-low method is used?