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

Month	Machine-Hours	Total Overhead Cost
April	52,000	$ 189,060
May	42,000	$ 164,260
June	62,000	$ 213,860
July	72,000	$ 238,660

Assume the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 42,000 machine-hour level of activity is:

Utilities (variable)	$ 54,600
Supervisory salaries (fixed)	42,000
Maintenance (mixed)	67,660
Total overhead cost	$ 164,260

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

Required:

1. Estimate how much of the $238,660 of overhead cost in July was maintenance cost. (Hint: To do this, it may be helpful to first determine how much of the $238,660 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 at an activity level of 47,000 machine-hours?