Nova Company's total overhead cost at various levels of activity are presented below:

Month	Machine-Hours	Total Overhead Cost
April	51,000	$ 195,630
May	41,000	$ 172,330
June	61,000	$ 218,930
July	71,000	$ 242,230

Assume that the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 41,000 machine-hour level of activity is:

Utilities (variable)	$ 45,100
Supervisory salaries (fixed)	63,000
Maintenance (mixed)	64,230
Total overhead cost	$ 172,330

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

1. Estimate how much of the $242,230 of overhead cost in July was maintenance cost. (Hint: to do this, it may be helpful to first determine how much of the $242,230 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 company's 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 46,000 machine-hours?