2007 AMC 12B Problem 2

Problem 2 of 25EasierAlgebra

A college student drove his compact car

120

miles home for the weekend and averaged

30

miles per gallon. On the return trip the student drove his parents’ SUV and averaged only

20

miles per gallon. What was the average gas mileage, in miles per gallon, for the round trip?

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Solution

The trip home uses

\frac{120}{30}=4

gallons, and the return trip uses

\frac{120}{20}=6

gallons. The round trip covers

240

miles on

10

gallons, so the average is

\dfrac{240}{10}=24.

Thus, the correct answer is B.