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2007 AMC 10B Problem 3

Problem 3 of 25EasierAlgebra

A college student drove his compact car 120120 miles home for the weekend and averaged 3030 miles per gallon. On the return trip the student drove his parents’ SUV and averaged only 2020 miles per gallon. What was the average gas mileage, in miles per gallon, for the round trip?

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Solution

The student used 12030=4\frac{120}{30}=4 gallons driving home and 12020=6\frac{120}{20}=6 gallons returning, for 1010 gallons over 240240 miles. The average is 24010=24\frac{240}{10} = 24 miles per gallon. Thus, the correct answer is B.

More practice

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Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.