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Thread: Escalator -- interesting Puzzle.

  1. #1
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    Escalator -- interesting Puzzle.

    An escalator is descending at constant speed. A walks down and takes 50 steps to reach the bottom. B runs down and takes 90 steps in the same time as A takes 10 steps.

    How many steps are visible when the escalator is not operating?

    -- James.


  2. #2
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    Re: Escalator -- interesting Puzzle.

    Really a very interesting puzzle. BUt I could not get it. I am stuck with the approach of finding the solution. Could someone give the answer and the method for solving the problem.


  3. #3
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    Re: Escalator -- interesting Puzzle.

    Actually the question was incomplete. I apologise for this.

    Here is the corrected one.


    An escalator is descending at constant speed. A walks down and takes 50 steps to reach the bottom. B runs down faster and takes 90 steps to reach the bottom.If B takes 90 steps in the same time as A takes 10 steps then how many steps are visible when the escalator is not operating?


    -- James.


  4. #4
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    Re: Escalator -- interesting Puzzle.

    James can you suggest the answer and the approach for getting the solution. Really a very interesting puzzle. But I am struck with the approach for solving it.


  5. #5
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    Re: Escalator -- interesting Puzzle.

    There are 100 steps in the esclator.

    Case : When A & B walk on unmoving surface
    --------------------------------------------
    10 Steps of A = 90 Steps of B .................... [Eq.1]
    => Speed of A : Speed of B :: 1 : 9
    => Time of A : Time of B :: 9 : 1

    Case : When A & B walk on esclator
    -----------------------------------
    Steps taken by B : 90
    TIme taken by B : T
    Steps taken by A : 50
    Time taken by A : 5T [From [Eq.1]]

    Time of A : Time of B :: 5 : 1

    let e be the number of steps moved by the esclator when A takes 1 step

    So

    (1+ e) / (9 + e) = 1/5
    => e = 1 step for every step of A

    A takes 50 steps
    => Esclator has moved by 50 steps
    Total number of steps = 50 + 50 = 100

    Cheers
    hsundar...


  6. #6
    Junior Member
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    Oct 2006
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    3

    Re: Escalator -- interesting Puzzle.

    I think some data are missing,Here is not clear that B reaches the bottom or not..


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