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Math Help - Word Problem help please

  1. #1
    AmandaCLong@aol.com
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    Word Problem help please

    A cyclist bikes x distance at 10 mph and returns over the same path at 8 mph. What is the cyclist's average rate for the round trip in miles per hour?

    (The answer given in the back of the book is 8.9. I don't understand how to get that answer -- my answer was 9)
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  2. #2
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    Quote Originally Posted by AmandaCLong@aol.com View Post
    A cyclist bikes x distance at 10 mph and returns over the same path at 8 mph. What is the cyclist's average rate for the round trip in miles per hour?

    (The answer given in the back of the book is 8.9. I don't understand how to get that answer -- my answer was 9)
    Just assume the distance is 80 miles.

    Then the amount of time for him to got at 10 m/h is 8 hours.

    And the amount of time for him to return at 8 m/h is 10 hours.

    Average speed is total distance divided by total time.
    The total distance was 80+80=160.
    The total times was 8+10=18.
    The average speed is 160/18=8.8888.. approximately 8.9 hours.

    As an excerise show that this is the same number no matter what assumed distance you take in the beginning.
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