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 11 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?  Choose one: A) 13 B) 13.5 C) 14 D) 14.5 E) 15.3
Ans is 13.5   Given d_ab = 2*d_bc   let d_ab = d and d_bc = x so d=2x   for average miles per gallon = (d+x)/((d/12)+(x/11)) = 15.3 (formula avg speed = total distance/ total time)
<result>B</result>
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 11 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?