So the Princeton Review says that if the answer to a data sufficiency can be found to be EITHER always YES or always NO, then the data is sufficient. This makes sense. HOWEVER, I am doing the Mcgraw-Hill Conquering Math book (2006 ed.) and for some of the questions, even when the answer is ALWAYS NO, it still says the correct answer is E (neither statements are sufficient). So I am wondering what will be correct on the actual GMAT?
As an example, this is Question 12:
Is the whole number N divisible by 3 or more positive integers?
1) N is a prime number
2) 0 < N < 4
1) This statement says N is a prime number, therefore N can only be divisible by 2 integers, 1 and itself. Thus, if N is a prime number, it is NEVER divisible by 3 or more integers and the answer is ALWAYS NO. Therefore, this statement is SUFFICIENT.
2). This statement says that N can be 1, 2, or 3. No matter which it is, N is not ever divisible by 3 or more positive integers. Again, the answer is always NO, that N is not divisible by 3 or more positive integers. Thus, this statement is also SUFFICIENT.
So... I thought the correct answer to this would be D. However, the book says that it is E... WHY?? This is confusing me as to how I should answer on the real test!!!
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DS - always yes, or always no
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It had the same logic for 2 other questions on the practice test I did.
So do you think I should ignore this and just go with the previous logic - that if a statement gives an answer that is always yes or always no, then the statement is sufficient?
So do you think I should ignore this and just go with the previous logic - that if a statement gives an answer that is always yes or always no, then the statement is sufficient?
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lunarpower
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if this book seriously posits (e) as the answer to this question (and to similar questions), then you should run for your life, and never open this book again.katty wrote:It had the same logic for 2 other questions on the practice test I did.
So do you think I should ignore this and just go with the previous logic - that if a statement gives an answer that is always yes or always no, then the statement is sufficient?
"definitive yes" is SUFFICIENT.
"definitive no" is SUFFICIENT.
"maybe" is INSUFFICIENT.
period.
that's the way the game is played.
interestingly, the OG11 and quant supplement contain NO problems for which "definitive no" is sufficient. that's right - EVERY SINGLE SUFFICIENT ANSWER to a yes/no problem in those books is "definitive yes".
this threw our staff into a commotion for a while - for some time, we actually wondered whether the test ever would include "definitive no" - but we've resolved that issue in the affirmative: there are examples of "definitive no = sufficient" in the GMATPREP software, as well as in GMATFOCUS.
so yeah, see what's written above.
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Agree with everything Ron said about the book. The answer is clearly D, not E. One comment about the OG, though-
I'd add that in my experience of the OG, GMATPrep, GMATFocus, and real GMAT tests, it is very rare to find a DS question where the statements do give you a 'definite no' answer, and I think some test prep books make a bit too big a deal about this issue - of course you should be aware of how to answer such a question, but it's pretty unlikely to be relevant on test day.
That is almost true. There is one (and only one) such question- no. 89 in the orange OG, 11th edition. The answer is a definite 'no' using either statement, and each statement is sufficient on its own.lunarpower wrote: interestingly, the OG11 and quant supplement contain NO problems for which "definitive no" is sufficient. that's right - EVERY SINGLE SUFFICIENT ANSWER to a yes/no problem in those books is "definitive yes".
I'd add that in my experience of the OG, GMATPrep, GMATFocus, and real GMAT tests, it is very rare to find a DS question where the statements do give you a 'definite no' answer, and I think some test prep books make a bit too big a deal about this issue - of course you should be aware of how to answer such a question, but it's pretty unlikely to be relevant on test day.
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lunarpower
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good call, man. respect.Ian Stewart wrote:Agree with everything Ron said about the book. The answer is clearly D, not E. One comment about the OG, though-
That is almost true. There is one (and only one) such question- no. 89 in the orange OG, 11th edition. The answer is a definite 'no' using either statement, and each statement is sufficient on its own.lunarpower wrote: interestingly, the OG11 and quant supplement contain NO problems for which "definitive no" is sufficient. that's right - EVERY SINGLE SUFFICIENT ANSWER to a yes/no problem in those books is "definitive yes".
I'd add that in my experience of the OG, GMATPrep, GMATFocus, and real GMAT tests, it is very rare to find a DS question where the statements do give you a 'definite no' answer, and I think some test prep books make a bit too big a deal about this issue - of course you should be aware of how to answer such a question, but it's pretty unlikely to be relevant on test day.
that's an EVIL question. "is blah blah blah for ALL numbers k, l, and m?"
this is sufficient because, no, it's definitely not that way for ALL numbers k, l, and m.
still, i could see getting this one wrong, despite totally knowing what's going on with it. here's what might happen:
* you'd realize the operation has to represent subtraction (for either statement)
* you'd realize that there are SOME k, l, m for which the statement is true (namely, exactly those cases when k = 0);
* you'd realize that there are OTHER k, l, m for which the statement is not true (namely, exactly those cases when k is not 0);
* you'd conclude that the statement is insufficient because it's "maybe".
this line of reasoning is incorrect, because "is blah blah blah for ALL numbers?" is a SINGLE yes/no question ABOUT THE WHOLE FUNCTION, not about the individual triples of k, l, m that you can plug into the function.
evil.
evil evil evil.
i've never actually noticed this question before.
Ron has been teaching various standardized tests for 20 years.
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Voit esittää kysymyksiä Ron:lle myös suomeksi
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