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Equal amounts of water - HELP

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gmatpup Rising GMAT Star Default Avatar
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Equal amounts of water - HELP Post Tue Jan 24, 2012 9:42 am
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    Please help! Thanks so much:)

    Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 full and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with the greater capacity, what fraction of the larger jar will be filled with water?

    A. 1/7
    B. 2/7
    C. 1/2
    D. 7/12
    E/ 2/3

    Answer is [/spoiler]C

    Please explain! Thanks again

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    pemdas GMAT Titan Default Avatar
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    Post Tue Jan 24, 2012 10:25 am
    double the amount of water in large jar, since the amounts of water are equal in both jars 1/4+1/4=1/2
    gmatpup wrote:
    Please help! Thanks so much:)

    Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 full and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with the greater capacity, what fraction of the larger jar will be filled with water?

    A. 1/7
    B. 2/7
    C. 1/2
    D. 7/12
    E/ 2/3

    Answer is [/spoiler]C

    Please explain! Thanks again

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    gmatpup Rising GMAT Star Default Avatar
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    Post Tue Jan 24, 2012 10:33 am
    but what about the 1/3?

    pemdas GMAT Titan Default Avatar
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    Post Tue Jan 24, 2012 10:58 am
    we need water not 1/3, the amounts are equal, if we pour into empty large jar one portion of water which makes 1/4 of the large jar, then additional portion of water (equal amount) will make another 1/4 added to it, 1/4+1/4=1/2


    gmatpup wrote:
    but what about the 1/3?

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    Brent@GMATPrepNow GMAT Instructor
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    Post Tue Jan 24, 2012 10:59 am
    gmatpup wrote:
    Please help! Thanks so much:)

    Equal amounts of water were poured into two empty jars of different capacities, which made one jar 1/4 full and the other jar 1/3 full. If the water in the jar with the lesser capacity is then poured into the jar with the greater capacity, what fraction of the larger jar will be filled with water?

    A. 1/7
    B. 2/7
    C. 1/2
    D. 7/12
    E/ 2/3

    Answer is [/spoiler]C

    Please explain! Thanks again
    The important point to note here is that equal volumes of water are poured into the two empty jars.

    We then take the jar with the lesser capacity and pour its water into the jar with the greater capacity.

    Which jar has the lesser capacity? The one that is 1/3 full or the one that is 1/4 full?

    Well, since both jars currently hold the same volume of water, the one that is 1/3 full must have the lesser capacity.

    So, we'll take the jar that is 1/3 full and pour its water into the jar that is 1/4 full.

    Since both jars contain the same volume of water, this action will double the amount of water that was in the jar that is 1/4 full.

    When we double the volume, that jar is now 1/2 full (1/4 + 1/4 = 1/2)

    Cheers,
    Brent

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    sk8legend408 Rising GMAT Star Default Avatar
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    Post Tue Jan 24, 2012 11:59 am
    This is actually a simple problem if you pick numbers...

    I picked 6 (liters or ounces) as the amount of water poured into each jar. The amounts each jar contain respectively are 6/24 and 6/18, or 1/4 and 1/3 respectively. The jar with less capacity, 6/18, is poured into the jar with more capacity, 6/24. (6+6)/24 = 12/24 = 1/2.

    The answer is C.

    ArunangsuSahu GMAT Destroyer! Default Avatar
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    Post Tue Jan 24, 2012 12:47 pm
    1/4+1/4=1/2

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