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Math Help - Minimum number of marbles to have taken one of each colour.

  1. #1
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    Minimum number of marbles to have taken one of each colour.

    Q9: In his pocket, a boy has 3 red marbles, 4 blue marbles, and 4 green
    marbles. How many will he have to take out of his pocket to ensure
    that he has taken out at least one of each color?
    A. 11
    B. 7
    C. 8
    D. 9
    how??
    Last edited by mr fantastic; February 11th 2011 at 02:30 AM. Reason: Re-titled.
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  2. #2
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    Quote Originally Posted by bahadarali View Post
    Q9: In his pocket, a boy has 3 red marbles, 4 blue marbles, and 4 green
    marbles. How many will he have to take out of his pocket to ensure
    that he has taken out at least one of each color?
    A. 11
    B. 7
    C. 8
    D. 9
    how??
    Consider the case that he took out the blue and the green marbles first (= 8 marbles). Then the next one must be a red one and he then has gotten all three colours.
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  3. #3
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    Well if the first 3 the took were red and the next 4 he took were blue, that would be seven, so the next one would have to be green and he would then have one of each colour.

    But if he took 4 blue then 4 green the next one would be red and that would make 9.

    The idea here is to add the 2 biggest numbers so there is no chance you can miss a colour.
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