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Re: If the length of each edge of a certain rectangular solid is an [#permalink]
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Hi TARGET730,

In the description of the rectangular solid, we're told that "4 of the faces have the same dimensions" - the ONLY way for that to occur is if the dimensions of the solid are X, X and Y (2 of the 3 dimensions MUST have the same length). We're also told that ALL the dimensions MUST be INTEGERS.

Using these restrictions, how many of your 'examples' actually match? You'll find that just one "fits" (the 4x4x8), so the final answer is

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Re: If the length of each edge of a certain rectangular solid is an [#permalink]
Ans is A
Length is integer, and 4 faces have equal areas
1) A1=32 and A2=16
from this LxB= 32 and \(B^2 = 16\), \(=> B= 4\) and \(L =8\) and Volume= 8x4x4 = 128 cu.units

or BxL =32 and \(L^2 = 16\), \(=> L=4\) and\(B = 8\) and in this case Volume = 4x4x8 = 128 cu. units

Note B and L cant take any other value as L is an integer mentioned in question.

2) \(L = 2B\) or \(B = 2L\)
Clearly statement is insufficient to answer about volume which is \(L^2\) x B or \(B^2\) x L
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If the length of each edge of a certain rectangular solid is an [#permalink]
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TARGET730 wrote:
If the length of each edge of a certain rectangular solid is an integer and exactly four of its faces have the same dimensions, then what is the volume of the rectangular solid?

(1) Two of the faces have areas of 32 square units and 16 square units.

(2) One of the edges is twice the length of another edge.


For the solid to have four faces with the same dimensions, two opposing faces must be SQUARES, as in the following figure:
In the figure above:
The area of the square base and the area of the square top = L*L.
The areas of the other four faces = L*H.

Statement 1:
Since the dimensions must all be integers, the rectangular solid must look as follows:

Since the dimensions of the solid are known, the volume can be determined.
SUFFICIENT.

Statement 2:
Since the dimensions of the solid are unknown, the volume cannot be determined.
INSUFFICIENT.

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Re: If the length of each edge of a certain rectangular solid is an [#permalink]
Statement 1 Since we are told that 4 faces have the same dimension and another 2 have a different dimension
it means one group of faces has an area of 32 and the second groups an area of 16. What's also apparent is that these 2 areas share one dimension : a length, a width or a height.
Now 32 = 32×1/16×2/4×8
16=16×1/4×4

Only 4×8 and 4×4 allow us to have 4 faces with an equal area and another 2 faces with a different area.The volume is thus 4×4×8=128.Sufficient

Statement 2 : From statement 1 we know 4×4×8 would work but we also know 2×2×4 would also work. Either of them gives us a different volume
Insufficient

Answer is A
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Re: If the length of each edge of a certain rectangular solid is an [#permalink]
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Re: If the length of each edge of a certain rectangular solid is an [#permalink]
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