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Manager
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GMAT Prep : odd and even [#permalink]
 31 Dec 2006, 21:18
Could some one please explain this to me
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Senior Manager
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nice question.... answer is A.
from stem we can infer that at least one from x,y,z is odd and at least one is even.
lets check st1. it is given that x(y+z) is even. can x be odd?
if it is, then (y+z) must be even, so they must have the same "oddity", and since there must be at least one even number, we can infer that y and z must be even if x is odd. however - this violates stem since in this arrangement xy+z is even.
so x cannot be odd - so it must be even. hence sufficient.
lets check st2
take x=1 y=2 z=3 and compare to y=1 x=2 z=3
both satisfy stem and st2, but in one x is odd and in the second x is even.
hence insufficient.
answer is A.
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Manager
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Good one, this was the question no 36 on the test and my mind was already fried (taking two tests in row)
Thanks, hobbit
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Director
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This was a good question. I took too much time to analyze this though. I can imagine I would have got it wrong on the test, esp if it came at the end of the test.
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close
