Werner Brothers, Inc., used the high-low method to derive its cost formula for electrical power cost. According to the cost formula, the variable cost per unit of activity is $2 per machine-hour. Total electrical power cost at the high level of activity was $9,400 and at the low level of activity was $9,000. If the high level of activity was 2,200 machine hours, then the low level of activity was:
A. 1,800 machine hours
B. 1,900 machine hours
C. 2,000 machine hours
D. 1,700 machine hours
