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this is from one of the 'hard math' princeton pdf's and i [#permalink]
05 Sep 2004, 21:00

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0% (00:00) correct
0% (00:00) wrong based on 0 sessions

this is from one of the 'hard math' princeton pdf's and i think their answer is wrong.

18. If x , y , and z are integers, is x / ( yz ) an integer?
(1) y is a factor of x more than once.
(2) All of the prime factors of z are also
factors of y .

My answer and theirs are below, PAGE DOWN a few times to see...

and yet, (zy) does not divide x, 2916 / 648 is not an integer.

the way i am reading it is, all the prime factors of z are factors of y. so 2 and 3 are factors of y, but not necessarily 3 ^ 3.

The way I read the question, I get that ALL the prime factors of z have to be factors of y. Therefore, if 3 happens to occur twice in z, then it must occur twice in y.

I think user is correct in the assumption on Prime factors. Otherwise, they would just be called factors. I support E too.
Btw, user, you might have meant, x = y * y = 144

The ans for the above example, x=144 y=12 z=54, is "No, x/yz is not an integet"
The ans for another example, x=25 y=5 z=5, is " "Yes, x/yz is an integer".
Hence, E.

I think user is correct in the assumption on Prime factors. Otherwise, they would just be called factors.

The reason they use prime factors in case of z and just factors in case of y is that if you don't do that, you'll be explicitly stating that y and z are the same numbers.

It's just a matter of semantics. Questions on the actual GMAT are usually not this ambigious.