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Homework Help: Thickness, Volume, Area.

  1. Dec 3, 2011 #1
    1. The problem statement, all variables and given/known data
    You use exactly 3.0 gallons of paint to paint the walls of a room that measures 12 meters long by 12 meters wide by 8.0 meters high. How thick is the layer of paint that you put on the four walls? (No windows or doors) Use the conversion 1 gallon = 3.79 x 10-3m3.

    2. Relevant equations
    Surface Area of a Rectangular Prism = 2ab + 2bc + 2ac
    Volume of a Rectangular Prism = a b c
    or Thickness= V/Area

    3. The attempt at a solution
    I converted the 3 gallons to m3 and got .01137 m3. I just am not really sure what to do next. I've tried playing around with the different formulas above, but nothing seems to come out right. The answer is supposed to be 3.0 x 10-5m. Seems like this question should be really easy...and it's making me feel really dumb for being unable to solve it. Any help would be much appreciated! Thanks!
  2. jcsd
  3. Dec 3, 2011 #2
    You should know that the area of the walls times the thickness of the paint folm is a volume, and you know what that volume is,

    V = 3 * [1 gallon = 3.79 x 10-3m3] = A * t

    A = 12*8 + 12*8 + 12*8 + 12*8

    Solve for t

    Good luck!
  4. Dec 3, 2011 #3


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    Homework Helper

    Don't forget you are not painting the roof or floor. What is the area of the walls? Area x Thickness = Volume of paint. It works out....
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