Nova Company's total overhead cost at various levels of activity are presented below: Month April May June July Machine-Hours Total Overhead Cost 50,000 $ 197,300 40,000 $ 171,400 60,000 $ 223,200 70,000 $ 249,100 Assume that the total overhead cost above consists of utilities, supervisory salaries, and maintenance. The breakdown of these costs at the 40,000 machine-hour level of activity is: Utilities (variable) Supervisory salaries (fixed) Maintenance (mixed) Total overhead cost $ 56,000 48,000 67,400 $ 171,400 Nova Company's management wants to break down the maintenance cost into its variable and fixed cost elements. Required: 1. Estimate how much of the $249,100 of overhead cost in July was maintenance cost. (Hint: to do this, it may be helpful to first determine how much of the $249,100 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 45,000 machine-hours?