Solve the Problem by Writing a Variation Model

Multiple Choice

Solve the problem by writing a variation model. The costs of a trucking company vary jointly with the number of trucks in service and the number of hours they are used. When 3 trucks are used for 7 hours each, the costs are $1,533. Find the costs of using 9 trucks, each for 13 hours.

A) $9,141
B) $9,441
C) $8,841
D) $9,741
E) $8,541