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

Month	Machine-Hours	Total Overhead Cost
April	46,000	$ 188,140
May	36,000	$ 160,240
June	56,000	$ 216,040
July	66,000	$ 243,940

Assume that the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 36,000 machine-hour level of activity is:

Utilities (variable)	$ 57,600
Supervisory salaries (fixed)	44,000
Maintenance (mixed)	58,640
Total overhead cost	$ 160,240

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

Required:

1. Estimate how much of the $243,940 of overhead cost in July was maintenance cost. (Hint: to do this, it may be helpful to first determine how much of the $243,940 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 41,000 machine-hours?