Song, Inc., uses the high-low method to analyze cost behavior. The company observed that at 22,000

machine hours of activity, total maintenance costs averaged $33.40 per hour. When activity jumped to

25,000 machine hours, which was still within the relevant range, the average total cost per machine hour

was $30.40.

54. On the basis of this information, the variable cost per machine hour was:

A. $8.40.

B. $22.00.

C. $25.00.

D. $30.40.

E. $33.40.