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Need help with this data sufficiency problem

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targetthegmat Just gettin' started! Default Avatar
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Need help with this data sufficiency problem Post Sun Feb 26, 2012 7:42 am
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  • Lap #[LAPCOUNT] ([LAPTIME])
    If x and y are integers, what is the ratio of 2x to y?
    8x3 = 27y3 (read x cube, y cube)
    4x2 = 9y2 (read x square, y square)

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    vijayrr007 Just gettin' started! Default Avatar
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    Post Sun Feb 26, 2012 10:15 am
    I think the answer is A. we get 2x=3y from 1 which means the ratio is 3:1. for 2 since its a square we are not sure whether its positive or negative. it can be 2x=3y or -2x=3y.
    targetthegmat wrote:
    If x and y are integers, what is the ratio of 2x to y?
    8x3 = 27y3 (read x cube, y cube)
    4x2 = 9y2 (read x square, y square)

    pemdas GMAT Titan Default Avatar
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    Post Sun Feb 26, 2012 7:28 pm
    targetthegmat wrote:
    If x and y are integers, what is the ratio of 2x to y?
    8x3 = 27y3 (read x cube, y cube)
    4x2 = 9y2 (read x square, y square)
    2x/y?
    st(1) 8x^3=27y^3 implies (2x)^3=(3y)^3 or 2x=3y which is Sufficient to answer 2x/y, as 2x/3y=1 and 3*(2x/3y)=3

    st(2) 4x^2=9y^2 implies (2x)^2=(3y)^2 or |2x|=|3y| Not Sufficient

    a

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    Post Mon Feb 27, 2012 3:21 am
    targetthegmat wrote:
    If x and y are integers, what is the ratio of 2x to y?
    8x3 = 27y3 (read x cube, y cube)
    4x2 = 9y2 (read x square, y square)
    (1) 8x^3 = 27y^3
    (2x)^3 = (3y)^3
    Taking cube root on both sides,
    2x = 3y
    2x : y = 3 : 1; SUFFICIENT.

    (2) 4x² = 9y²
    Taking square root on both sides,
    ±2x = 3y; NOT sufficient.

    The correct answer is A.

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    spideygirl Just gettin' started! Default Avatar
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    Post Sat Apr 27, 2013 1:34 pm
    Hi, I have a question. I had picked (E) because I took the scenario of x and y being set to 0. Is it incorrect to use 0 as a value to plug in for x and y? Can we not take zero for both because x and y are two different variables?

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