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Re: Barbara walked up and down a 25 meter long corridor. When she walked [#permalink]
Expert Reply
As the distance is constant, the average speed will be the harmonic average of given speeds

Average speed: \(\frac{2ab }{a + b} = \frac{2 * 4 * 2 }{ 4 + 2} = \frac{16 }{ 6} = \frac{8}{3}\)

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Barbara walked up and down a 25 meter long corridor. When she walked [#permalink]
Bunuel wrote:
Barbara walked up and down a 25 meter long corridor. When she walked one way, she walked at 4 meters per second, and when she walked the other way, her speed was 2 meters per second. What was her average speed in meters per second?


A. \(1 \frac{1}{3}\)

B. \(1 \frac{2}{3}\)

C. \(2 \frac{1}{3}\)

D. \(2 \frac{2}{3}\)

E. 3



Av Speed = Total Distance/ Total Time = (25+25)/(25/4 + 25/2)= 8/3= \(2 \frac{2}{3}\)

D
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Barbara walked up and down a 25 meter long corridor. When she walked [#permalink]
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