Nova Companys total overhead cost at various levels of activity are presented below:

Month	Machine- Hours			Total Overhead Cost
April		70,000		$	198,000
May		60,000		$	174,000
June		80,000		$	222,000
July		90,000		$	246,000

Assume that the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 60,000 machine-hour level of activity is:

Utilities (variable)	$	48,000
Supervisory salaries (fixed)		21,000
Maintenance (mixed)		105,000
Total overhead cost	$	174,000

Nova Companys management wants to break down the maintenance cost into its variable and fixed cost elements.

Required:

1. Estimate how much of the $246,000 of overhead cost in July was maintenance cost. (Hint: to do this, it may be helpful to first determine how much of the $246,000 consisted of utilities and supervisory salaries. Think about the behavior of variable and fixed costs.)

2. Using the high-low method, estimate a cost formula for maintenance in the form Y = a + bX.

3. Express the companys total overhead cost in the form Y = a + bX.

4. What total overhead cost would you expect to be incurred at an activity level of 75,000 machine-hours