Problem:
It takes Mary 30 minutes to walk uphill from her home to school, but it takes her only 10 minutes to walk from school to home along the same route. What is her average speed, in , for the round trip?
Answer Choices:
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B.
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E.
Solution:
Mary walks a total of in 40 minutes. Because 40 minutes is , her average speed, in , is .
The problems on this page are the property of the MAA's American Mathematics Competitions