66. The Chambers Manufacturing Company recorded overhead costs of $14,182 at an activity level of 4,200 machine hours and $8,748 at 2,300 machine hours. The records also indicated that overhead of $9,730 was incurred at 2,600 machine hours. What is the variable cost per machine hour using the high-low method to estimate the cost equation? a. $2,78 E. $2.86 c. $3.10 d. $3.38 e. some other