BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

xy<0

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
Master | Next Rank: 500 Posts
Posts: 131
Joined: Fri Jun 18, 2010 10:19 am
Location: New York, NY
Thanked: 10 times

by aleph777 » Wed Jan 12, 2011 2:41 pm
Night reader,

Can this have a solution?

If xy < 0, then either x or y must be < 0.

STATEMENT 1: From (y^2)x > 0 we know y^2 is positive, and x must also be positive in order to be > 0. But since we don't know the value of y, INSUFFICIENT.

STATEMENT 2: From (x^2)y > 0 we know that x^2 is positive, and therefore y must be in order for the phrase to be > 0. But here we don't know the value of x, INSUFFICIENT.

COMBINED: This is where I'm confused... Statement 1 says x is positive. Statement 2 says y is positive... So xy > 0. But that contradicts the initial statement... Am I doing something wrong?
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 543
Joined: Tue Jun 15, 2010 7:01 pmFollowed by: 3 members
Thanked: 147 times

by anshumishra » Wed Jan 12, 2011 3:18 pm
Night reader wrote:If xy < 0, is y < 0?

(1) (y^2)*x > 0
(2) (x^2)*y > 0
xy < 0, is y<0 ?

(1) (y^2)*x > 0
=> (+ve)*x > 0
=> x > 0
So, xy < 0 => y< 0 --- Sufficient

(2)(x^2)*y > 0
=> (+ve)*y > 0
=> y > 0 ----- Sufficient

So, answer is D. Although as per GMAT style(as x has different signs in the two statements), it is not good.
Thanks
Anshu

(Every mistake is a lesson learned )
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 132
Joined: Mon Jan 10, 2011 12:26 pmFollowed by: 37 members
Location: New York City
Thanked: 68 times
GMAT Score:780

by Adam@Knewton » Wed Jan 12, 2011 3:19 pm
aleph777 wrote:Night reader,

Can this have a solution?

If xy < 0, then either x or y must be < 0.

STATEMENT 1: From (y^2)x > 0 we know y^2 is positive, and x must also be positive in order to be > 0. But since we don't know the value of y, INSUFFICIENT.

STATEMENT 2: From (x^2)y > 0 we know that x^2 is positive, and therefore y must be in order for the phrase to be > 0. But here we don't know the value of x, INSUFFICIENT.

COMBINED: This is where I'm confused... Statement 1 says x is positive. Statement 2 says y is positive... So xy > 0. But that contradicts the initial statement... Am I doing something wrong?
Aleph: You are correct that this problem is "broken" because the Statements contradict the informatino given in the Prompt, and therefore could not be a real GMAT question. However, note that it isn't a Value question. If we change the prompt to "If xy > 0," then it makes sense; I'll bet if you re-think your deductions based on what the question is really asking for, you'll see a different answer...

[spoiler]All we need is the sign of y, and because xy>0 (or xy<0, either one works for this), knowing the sign of x tells us the sign of y. Thus, either statement is Sufficient, and the answer is D.[/spoiler]
Prep Smarter, Score Higher
www.knewton.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pmFollowed by: 10 members
Thanked: 127 times

by Night reader » Wed Jan 12, 2011 3:28 pm
AdamKnewton wrote:
aleph777 wrote:Night reader,

Can this have a solution?

If xy < 0, then either x or y must be < 0.

STATEMENT 1: From (y^2)x > 0 we know y^2 is positive, and x must also be positive in order to be > 0. But since we don't know the value of y, INSUFFICIENT.

STATEMENT 2: From (x^2)y > 0 we know that x^2 is positive, and therefore y must be in order for the phrase to be > 0. But here we don't know the value of x, INSUFFICIENT.

COMBINED: This is where I'm confused... Statement 1 says x is positive. Statement 2 says y is positive... So xy > 0. But that contradicts the initial statement... Am I doing something wrong?
Aleph: You are correct that this problem is "broken" because the Statements contradict the informatino given in the Prompt, and therefore could not be a real GMAT question. However, note that it isn't a Value question. If we change the prompt to "If xy > 0," then it makes sense; I'll bet if you re-think your deductions based on what the question is really asking for, you'll see a different answer...

[spoiler]All we need is the sign of y, and because xy>0 (or xy<0, either one works for this), knowing the sign of x tells us the sign of y. Thus, either statement is Sufficient, and the answer is D.[/spoiler]
Hi Adam, we are not supposed to post the real GMAT questions here ;)
signs are different- yes, the question is not asking one value... so we are not limited to the one single solution, style might be ok
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 132
Joined: Mon Jan 10, 2011 12:26 pmFollowed by: 37 members
Location: New York City
Thanked: 68 times
GMAT Score:780

by Adam@Knewton » Wed Jan 12, 2011 3:33 pm
Night reader wrote:
AdamKnewton wrote:
aleph777 wrote:Night reader,

Can this have a solution?

If xy < 0, then either x or y must be < 0.

STATEMENT 1: From (y^2)x > 0 we know y^2 is positive, and x must also be positive in order to be > 0. But since we don't know the value of y, INSUFFICIENT.

STATEMENT 2: From (x^2)y > 0 we know that x^2 is positive, and therefore y must be in order for the phrase to be > 0. But here we don't know the value of x, INSUFFICIENT.

COMBINED: This is where I'm confused... Statement 1 says x is positive. Statement 2 says y is positive... So xy > 0. But that contradicts the initial statement... Am I doing something wrong?
Aleph: You are correct that this problem is "broken" because the Statements contradict the informatino given in the Prompt, and therefore could not be a real GMAT question. However, note that it isn't a Value question. If we change the prompt to "If xy > 0," then it makes sense; I'll bet if you re-think your deductions based on what the question is really asking for, you'll see a different answer...

[spoiler]All we need is the sign of y, and because xy>0 (or xy<0, either one works for this), knowing the sign of x tells us the sign of y. Thus, either statement is Sufficient, and the answer is D.[/spoiler]
Hi Adam, we are not supposed to post the real GMAT questions here ;)
signs are different- yes, the question is not asking one value... so we are not limited to the one single solution, style might be ok
Night Reader:

You're right, of course this isn't a real GMAC question, because that would violate our terms of service -- but it is worth noting that, as Aleph pointed out above, this question violates the rules of Data Sufficiency, because Statements (1) and (2) taken together imply that x>0 and that y>0, even though we're told that xy<0. One of the most difficult tasks when tweaking a real question so that it is similar to, but different from, a real GMAC question is making sure that weird inconsistencies don't pop up. In the industry we call this SBDing (it stands for "Same-But-Different"). The only reason it's worth pointing out is that otherwise, it could confuse some test-takers.

Thanks for the interesting question!
Prep Smarter, Score Higher
www.knewton.com
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 1337
Joined: Sat Dec 27, 2008 6:29 pmFollowed by: 10 members
Thanked: 127 times

by Night reader » Wed Jan 12, 2011 4:11 pm
the reasons that this DS CAN'T BE GMAT question:
there's only one answer - yes or no. this DS has two answers -yes,no or no,yes :)
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Master | Next Rank: 500 Posts
Posts: 243
Joined: Sun Jul 12, 2009 7:12 amFollowed by: 2 members
Location: Dominican Republic
Thanked: 31 times
GMAT Score:480

by MAAJ » Thu Jan 13, 2011 5:17 am
Statements contradict eachother... and GMAT only presents TRUE information on each statements, so y cannot be <0 and >0 at the same time. Correct answer: [spoiler]Not a real GMAT question :)[/spoiler]
"There's a difference between interest and commitment. When you're interested in doing something, you do it only when circumstance permit. When you're committed to something, you accept no excuses, only results."
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1