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Homework Help: Related rates?

  1. Oct 25, 2009 #1
    1. The problem statement, all variables and given/known data
    a) A cubical box is to be built so that it holds 125 cm3. How precisely should the edge be made so
    that the volume will be corrected to within 3 cm3?

    3. The attempt at a solution

    I am not sure even what this is asking exactly could someone decode if they have seen a similar problem before?
  2. jcsd
  3. Oct 25, 2009 #2


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    Homework Helper

    Yeah, it's just a differential problem, I think. V=a^3, so dV=3*a^2*da. If a=5cm then V=125cm^3. You are given dV=3cm^3. Solve for da. It's an approximate solution for how large the variation in a can be and still give you a V between 128cm^3 and 122cm^3. Approximate, mind you.
  4. Oct 25, 2009 #3
    I thought that the question might be asking something like that but it seemed kind of strange to me. thanks
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