GMAT Math : DSQ: Calculating the surface area of a cube
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Example Questions
Example Question #11 : Cubes
Ron is making a box in the shape of a cube. He needs to know how much wood he needs. Find the surface area of the box.
I) The diagonal distance across the box will be equivalent to 
II) Half the length of one side is 
Either statement is sufficient to answer the question.
Statement II is sufficient to answer the question, but Statement I is not sufficient to answer the question.
Both statements are needed to answer the question.
Neither statement is sufficient to answer the question. More information is needed.
Statement I is sufficient to answer the question, but Statement II is not sufficient to answer the question.
Either statement is sufficient to answer the question.
To find the surface area of a cube, we need the length of one side.
Statement I gives the diagonal, we can use this to find the length of one side.
Statement II gives us a clue about the length of one side; we can use that to find the full length of one side.
The following formula gives us the surface area of a cube:
Use Statement I to find the length of the side with the following formula, where 
So, using Statement I, we find the surface area to be
Using Statement, we get that the length of one side is two times two:
Again, use the surface area formula to get the following:
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