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Thread: Bridge Crossing

  1. #1
    5 Star Lounger Maudibe's Avatar
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    Bridge Crossing

    Four members of a band are walking to a night concert. They decide to take a shortcut, but must cross a bridge. Luckily they have one flashlight. Because of the varying size of their instruments, it takes each member a different amount of time to cross the bridge - it takes the first person one minute, the second person two minutes, the third person five minutes and the fourth person ten minutes. They must cross the bridge in pairs, travelling at the slower speed so if the one minute person went with the ten minute person, it would take a total of ten minutes. Since there is only one flashlight, one person must come back across the bridge, then another pair can cross. They only have 17 minutes to cross the bridge and still get to the concert on time. What order should they cross to get everyone across and get to the concert?

    glhf,
    Maud

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  3. #2
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    Quote Originally Posted by Maudibe View Post
    Four members of a band are walking to a night concert. They decide to take a shortcut, but must cross a bridge. Luckily they have one flashlight. Because of the varying size of their instruments, it takes each member a different amount of time to cross the bridge - it takes the first person one minute, the second person two minutes, the third person five minutes and the fourth person ten minutes. They must cross the bridge in pairs, travelling at the slower speed so if the one minute person went with the ten minute person, it would take a total of ten minutes. Since there is only one flashlight, one person must come back across the bridge, then another pair can cross. They only have 17 minutes to cross the bridge and still get to the concert on time. What order should they cross to get everyone across and get to the concert?

    glhf,
    Maud
    1+2 2 min
    1 returns 1 min
    5+10 10 min
    2 returns 2 min
    1+2 2 min

    total 17 min

  4. #3
    5 Star Lounger Maudibe's Avatar
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    And there you have it! Good job!

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    Incorrect I say! 2 can return WITHOUT his instrument which should reduce the time to 1 minute rather than 2 for a total of 16 minutes!

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    How can you assume they all walk the same speed w/o their instruments?

  7. #6
    5 Star Lounger Maudibe's Avatar
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    I like to know how they even arrived at the bridge at the same time. Dmspen, I never go anywhere without my instrument!

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