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Math Help - another puzzle

  1. #1
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    another puzzle

    2. Four persons can cross a bridge in 3,7,13,17 minutes. Only two can cross at a time. find the

    minimum time taken by the four to cross the bridge.

    ans:20
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  2. #2
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    Quote Originally Posted by bharathlece
    2. Four persons can cross a bridge in 3,7,13,17 minutes. Only two can cross at a time. find the

    minimum time taken by the four to cross the bridge.

    ans:20
    1)Send the 17 and the 13.
    2)After 13 min, 13-guy finished and 17-guy walked for 13 min, there is room for another.
    3)Now send the 7 minute guy.
    4)After 4 min, the 17-guy finished and 7-guy waled for 4 min, there is room for another.
    5)Send the 3 minute guy.
    6)After 3 minutes both the 3 and 4 guys finished on time.
    In total 20 minutes where used.
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  3. #3
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    thanku man

    hi, thanks for giving me replay.
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