Martin Company makes cell phones. The company controller wanted to calculate the fixed and variable costs associated with electricity use in the factory. Data for the past four months were collected.

	Electricity	Machine
Month	cost	hours
January	$7,560	570
February	8,220	625
March	7,480	546
April	7,186	518

Coefficients shown by a regression program are:

Intercept	2,255
X Variable 1	9.48

Using the results of regression, the cost formula for electricity cost was

	a.	$9.48 machine hours
	b.	$2,255 machine hours
	c.	$2,255 + ($9.48 machine hours)
	d.	None of these are correct.