Selected data about Ruby Company's manufacturing operations at two levels of activity are given below:

6. Selected data about Ruby Company's manufacturing operations at two levels of activity are given below Number of units produced Total costs Direct material cost per unit Direct labor cost per unit 10,000 15,000 S157zooo 925,000 a. Using the high-low method, estimate the cost formula for manufacturing overhead. Assume that both direct material and direct labor are variable costs. What is the purpose of knowing the cost formula?