mondirachakraborty wrote:

Bunuel, will you please provide us with an easy solution? I have gone through the OE part but wasn't able to understand.

gmatexam439 wrote:

My approach was similar to what has been explained by Mike and took me around 2 and a half minutes to solve. But Please clarify do such questions come in GMAT? Its pure thought process, breaking up a 10x10 into different pieces like a matrix movie, i mean pure imagination and no mathematical concept used.

Dear

mondirachakraborty &

gmatexam439,

I'm happy to respond.

First of all,

mondirachakraborty, this is a HARD question. Some questions on the GMAT look hard but there's some simplifying trick. For this question, there's no easy trick: the question is quick only if you have the spatial/visual intuition to think through the ideas in the OE quickly. My friend, if you are asking for some way for the hard to be made easy for you, you are asking the wrong question. The question is how to rise to the challenge of what you now find hard, so that eventually it can seem easy to you. If you find an OE that you don't understand, don't look for a way to evade it. Instead, dig deeper into anything you don't understand. Dissect it line by line. If there are particular points that you don't understand. ask me (the author of this question) about those very specific questions. Education is not something experts such as Bunuel and I do to you: instead, education is a process you do to yourself, by yourself, and for yourself. It depends primarily on your dedication, diligence, and engagement. Go all in, and we experts will do whatever we can to support you.

And,

gmatexam439, this is a hard question, probably about at about the upper limit of what the CAT would throw at a student who is acing everything else in the Quant section. In the OE, i spelled out everything in meticulous detail, but if you have good spatial intuition, you might be able to do this in under 20 seconds. We need four corners--more than enough corners. We need 32 edges--more than enough edges and left over corners, so we are covered. For everything else, we just need one side painted, so the only ones that need paint are the unpainted "inner cubes," the 1 inside the 3x3x3 and the 8 inside the 4x4x4. (Any cube of nxnxn has an inner cube of (n-2)x(n-2)x(n-2) that doesn't see the light of day.) Paint 9 faces and we are all set. As with many challenging Quant questions, it's simply a matter of mentally dissecting the scenario in the right way: when you do that, the answer simply appears.

Does all this make sense?

Mike

_________________

Mike McGarry

Magoosh Test Prep

Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)