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Math Help - Related Rates

  1. #1
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    Related Rates

    If the volume of a cube is increasing at 24 in^3/min and the surface area of the cube is increasing at 12in^2/min
    , what is the length of each edge of the cube?
    A. 2
    B 2 \sqrt{2}
    C. 12^{1/3}
    D. 4
    E. 8

    Answers are in inches.

    This is what I know:
    Dv/dt= 24
    and DSA/dt= 12

    v= s^3
    SA= 3s...I think

    So,
    Dv/dt= 3s ds/dt
    dSA/dt= 2 ds/dt

    Ds/dt= \frac{dv/dt}{3s}

    Now what?

    Thanks!
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  2. #2
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    Surface Area of a Cube is 6s^{2}.
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