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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## GMATPrep 2 tagged by: Brent@GMATPrepNow ##### This topic has 5 expert replies and 1 member reply ## GMATPrep 2 Attached. _________________ Please press "thanks" if you think my post has helped you.. Cheers!! ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15388 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 Quote: Is xy > 0 ? 1. x - y > -2 2. x - 2y < -6 Statement 1: x > y-2 If y=2 and x=1, is 1*2 > 0? Yes. If y=-1 and x=1, is 1*(-1) > 0? No. Since the answer is YES in the first case but NO in the second case, INSUFFICIENT. Statement 2: x < 2y-6 If y=1 and x=-10, is 1*(-10) > 0? No. If y=10 and x=1, is 1*10 > 0? Yes. Since the answer is NO in the first case but YES in the second case, INSUFFICIENT. Statements combined: Linking together the two statements, we get: y-2 < x < 2y-6 y-2 < 2y-6 y > 4. Since y > 4 and x > y-2, we know that x > 2. Thus, x and y are both positive, with the result that xy > 0. SUFFICIENT. The correct answer is C. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Last edited by GMATGuruNY on Tue Feb 03, 2015 6:57 am; edited 2 times in total Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 13046 messages Followed by: 1253 members Upvotes: 5254 GMAT Score: 770 Quote: Is xy > 0 ? 1. x - y > -2 2. x - 2y < -6 Target question: Is xy>0? Statement 1: x-y > -2 There are several pairs of numbers that meet this condition. Here are two: Case a: x = 5 and y = 1, in which case xy is greater than 0 Case b: x = 5 and y = -1, in which case xy is not greater than 0 Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT Statement 2: x - 2y < -6 There are several pairs of numbers that meet this condition. Here are two: Case a: x = 1 and y = 5, in which case xy is greater than 0 Case b: x = -1 and y = 5, in which case xy is not greater than 0 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT Statements 1 and 2 combined: Here's what we know: x-y > -2 x-2y < -6 Since both inequalities have an x, let's isolate x in both of them to get: y-2 < x x < 2y-6 Aside: Notice that I rewrote them so that the 2 inequality symbols are pointing in the same direction. Now we can combine these inequalities to get: y-2 < x < 2y-6 Next, remove the x to get: y-2 < 2y-6 Then subtract y from both sides and add 6 to both sides to get: 4 < y Great, we now know that y is positive. Also, if y-2 < x (and y>4), then we know that x must also be positive Since we now know that x and y are positive, we can be certain that xy is greater than 0 So, the answer is C Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert GMAT Instructor Joined 04 Dec 2012 Posted: 2094 messages Followed by: 240 members Upvotes: 1443 Mitch, I think you accidentally posted the solution to the wrong question! I'll add 2 things to Brent's great explanation: a) As I'm sure you know, any time you see an inequality relative to 0, frame your question in terms of positives and negatives. Is xy > 0? Rephrased question: do x and y have the same sign? Brent gave good examples of testing numbers to prove that x and y could have the same sign or different signs with each statement individually. b) If you'd prefer not to isolate x first, you can combine the inequalities by simply flipping the second one around: x - 2y < -6 --> -6 > x - 2y Now, line up the inequalities and you can add them together: x - y > -2 -6 > x - 2y _______________ x - y - 6 > x - 2y - 2 Simplify: -y - 6 > -2y - 2 y - 6 > -2 y > 4 Substitute: x - (grt 4) > -2 x > 2 x and y are both positive, so together the statements are sufficient. _________________ Ceilidh Erickson Manhattan Prep GMAT & GRE instructor EdM in Mind, Brain, and Education Harvard Graduate School of Education Manhattan Prep instructors all have 99th+ percentile scores and expert teaching experience. Sign up for a FREE TRIAL, and learn why we have the highest ratings in the GMAT industry! Free Manhattan Prep online events - The first class of every online Manhattan Prep course is free. Classes start every week. ### GMAT/MBA Expert GMAT Instructor Joined 25 May 2010 Posted: 15388 messages Followed by: 1872 members Upvotes: 13060 GMAT Score: 790 ceilidh.erickson wrote: Mitch, I think you accidentally posted the solution to the wrong question! Thanks for pointing this out, Ceilidh. My post above now offers a solution to the correct question. _________________ Mitch Hunt Private Tutor for the GMAT and GRE GMATGuruNY@gmail.com If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at GMATGuruNY@gmail.com. Student Review #1 Student Review #2 Student Review #3 Free GMAT Practice Test How can you improve your test score if you don't know your baseline score? Take a free online practice exam. Get started on achieving your dream score today! Sign up now. Senior | Next Rank: 100 Posts Joined 12 Mar 2013 Posted: 44 messages Upvotes: 3 but if substitute in 2nd equation does not hold? y>4 -6 > x - 2y -6> x - 2(grt4) -6> x -grt8 grt 2 > x x could be 0 or neg ? ### GMAT/MBA Expert GMAT Instructor Joined 12 Sep 2012 Posted: 2635 messages Followed by: 117 members Upvotes: 625 Target GMAT Score: V51 GMAT Score: 780 J N, I'd think of it this way. x - y > -2, or x > y - 2. Since y > 4, y - 2 > 2. We know that x > y - 2, so x > 2. Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! • FREE GMAT Exam Know how you'd score today for$0

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