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 Post subject: GMAT 3D Geometry
PostPosted: Thu May 21, 2009 9:04 pm 
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Joined: Thu May 21, 2009 8:50 pm
Posts: 2
Hi,
Regarding Test question 10 math test 2? (10cm cube on it's side is composed of 1cm cubes on their side etc..)

Can you explain to me how you get 8*8*8 = 512 cubes inside with no sides that could be painted?

Thanks in advance for your help.

Mary Kay Richardson.


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 Post subject: Re: Test question 10 math test 2?
PostPosted: Mon May 25, 2009 10:48 am 
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Joined: Mon Apr 06, 2009 5:44 pm
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Envision two cubes. One embedded within the other. The larger cube is a 10 x 10 x 10 cube. The inner cube must be an 8 x 8 x 8 cube since if we pull out the 8 corner cubes (ones with 4 painted faces) and then the 12 rows of cubes in between the corner cubes from each of the edges, we are left with the paintless cube which runs 8x8x8 cubes in dimension.

So there are 8x8x8=512 paintless cubes


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