2009 AMC 8 Problems/Problem 14
Contents
Problem
Austin and Temple are miles apart along Interstate 35. Bonnie drove from Austin to her daughter's house in Temple, averaging
miles per hour. Leaving the car with her daughter, Bonnie rode a bus back to Austin along the same route and averaged
miles per hour on the return trip. What was the average speed for the round trip, in miles per hour?
Solution
The way to Temple took hours, and the way back took
for a total of
hours. The trip is
miles. The average speed is
miles per hour.
Solution 2
This question simply asks for the harmonic mean of and
, regardless of how far Austin and Temple are.
Plugging in, we have:
miles per hour.
See Also
2015 Problem 17
2009 AMC 8 (Problems • Answer Key • Resources) | ||
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Followed by Problem 15 | |
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