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In Episode 4 of our GMAT Ninja CR series, we tackle the most intimidating CR question type: Boldface & "Legalese" questions. If you've ever stared at an answer choice that reads, "The first is a consideration introduced to counter a position that...- May 14
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Most GMAT test-takers are intimidated by the hardest GMAT Verbal questions. In this session, Target Test Prep GMAT instructor Erika Tyler-John, a 100th percentile GMAT scorer, will show you how top scorers break down challenging Verbal questions..
16 Sep 2014, 01:08
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16 Sep 2014, 01:08
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Official Solution:
Is \(x^2y^3z^2 > 0\)?
For \(x^2y^3z^2\) to be positive \(x\) and \(z\) must not be 0 (in this case even powers would guarantee that \(x^2z^2\) is strictly positive and not only non-negative) and \(y\) must be positive.
(1) \(xy > 0\)
From this statement we can deduce that \(x\) is not 0. However, we don't know whether \(z\) is 0 or not, and also don't know the sign of \(y\). Not sufficient.
(2) \(yz < 0\)
From this statement we can deduce that \(z\) is not 0. However, we don't know whether \(x\) is 0 or not, and also don't know the sign of \(y\). Not sufficient.
(1)+(2) We know that neither \(x\) nor \(z\) is 0. However, the sign of \(y\) is still not known. For example, consider the case when \(x\) is positive, \(y\) is positive, and \(z\) is negative, giving a YES answer to the question and the case when \(x\) is negative, \(y\) is negative, and \(z\) is positive, giving a NO answer to the question. Not sufficient.
Answer: E
Is \(x^2y^3z^2 > 0\)?
For \(x^2y^3z^2\) to be positive \(x\) and \(z\) must not be 0 (in this case even powers would guarantee that \(x^2z^2\) is strictly positive and not only non-negative) and \(y\) must be positive.
(1) \(xy > 0\)
From this statement we can deduce that \(x\) is not 0. However, we don't know whether \(z\) is 0 or not, and also don't know the sign of \(y\). Not sufficient.
(2) \(yz < 0\)
From this statement we can deduce that \(z\) is not 0. However, we don't know whether \(x\) is 0 or not, and also don't know the sign of \(y\). Not sufficient.
(1)+(2) We know that neither \(x\) nor \(z\) is 0. However, the sign of \(y\) is still not known. For example, consider the case when \(x\) is positive, \(y\) is positive, and \(z\) is negative, giving a YES answer to the question and the case when \(x\) is negative, \(y\) is negative, and \(z\) is positive, giving a NO answer to the question. Not sufficient.
Answer: E
12 Oct 2023, 04:00
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I have edited the question and the solution by adding more details to enhance its clarity. I hope it is now easier to understand.
