lheiannie07 wrote:A certain car traveled twice as many miles from Town A to Town B as it did from Town B to Town C. From Town A to Town B, the car averaged 12 miles per gallon, and from Town B to Town C, the car averaged 18 miles per gallon. What is the average miles per gallon that the car achieved on its trip from Town A through Town B to Town C?
A. 13
B. 13.5
C. 14
D. 14.5
E. 15
Let B to C = 18 miles.
Since the rate from B to C is 18 miles per gallon, the amount of gas used from B to C = d/r = 18/18 = 1 gallon.
Since the distance from A to B is twice the distance from B to C, A to B = 2*18 = 36 miles.
Since the rate from A to B is 12 miles per gallon. the amount of gas used from A to B = d/r = 36/12 = 3 gallons.
Thus:
Average miles per gallon for the whole trip = (total distance)/(total gas) = (18+36)/(1+3) = 54/4 = 27/2 = 13.5 miles per gallon.
The correct answer is
B.
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