Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
GMAT Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Dec 1310:00 AM EST
-12:00 PM EST
Have you ever wondered how to score a PERFECT 805 on the GMAT? Meet Julia, a banking professional who used the Target Test Prep course to achieve this incredible feat. Julia's story is nothing short of an inspiration.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.
Dec 1411:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.- Dec 15
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. 
Dec 1608:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes!
Updated on: 30 Sep 2018, 04:58
Originally posted by MathRevolution on 11 Jun 2018, 06:35.
Last edited by Bunuel on 30 Sep 2018, 04:58, edited 7 times in total.
Last edited by Bunuel on 30 Sep 2018, 04:58, edited 7 times in total.
Kudos
Bookmarks
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
63% (01:16) correct
37%
(01:16)
wrong
based on 49
sessions
History
Date
Time
Result
Not Attempted Yet
Updated on: 30 Sep 2018, 04:58
Originally posted by MathRevolution on 11 Jun 2018, 06:35.
Last edited by Bunuel on 30 Sep 2018, 04:58, edited 3 times in total.
Last edited by Bunuel on 30 Sep 2018, 04:58, edited 3 times in total.
Kudos
Bookmarks
Official Solution:
Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
The first step of the VA (Variable Approach) method is to modify the original condition and the question, and then recheck the question. In inequality questions, the law "Question is King" tells us that if the solution set of the question includes the solution set of the condition, then the condition is sufficient
Modifying the question:
\(x^2-x>0\)
\(x(x-1) > 0\)
\(x < 0\) or \(x > 1\) by the "LLGG" rule.
Condition 1): \(x > 0\)
Since the solution set of the question does not include the solution set of condition 1), condition 1) is not sufficient.
Condition 2):
\(x^3+x>0\)
\(x(x^2+1)>0\)
\(x>0\), since \(x^2+1 > 0\) is always true.
Condition 2) is equivalent to the condition 1), so it is not sufficient.
Conditions 1) & 2)
We have x >0 only from both conditions together.
Since the solution set of the question does not include the solution set of conditions 1) and 2) together, they are not sufficient.
Therefore, the answer is E.
Answer: E
If the original condition includes "1 variable", or "2 variables and 1 equation", or "3 variables and 2 equations" etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
Answer: E
Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
The first step of the VA (Variable Approach) method is to modify the original condition and the question, and then recheck the question. In inequality questions, the law "Question is King" tells us that if the solution set of the question includes the solution set of the condition, then the condition is sufficient
Modifying the question:
\(x^2-x>0\)
\(x(x-1) > 0\)
\(x < 0\) or \(x > 1\) by the "LLGG" rule.
Condition 1): \(x > 0\)
Since the solution set of the question does not include the solution set of condition 1), condition 1) is not sufficient.
Condition 2):
\(x^3+x>0\)
\(x(x^2+1)>0\)
\(x>0\), since \(x^2+1 > 0\) is always true.
Condition 2) is equivalent to the condition 1), so it is not sufficient.
Conditions 1) & 2)
We have x >0 only from both conditions together.
Since the solution set of the question does not include the solution set of conditions 1) and 2) together, they are not sufficient.
Therefore, the answer is E.
Answer: E
If the original condition includes "1 variable", or "2 variables and 1 equation", or "3 variables and 2 equations" etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
Answer: E
26 Jul 2018, 18:35
Kudos
Bookmarks
I don't agree with the explanation. I believe this question is mistaking one of the solutions x < 0, for the first condition x >0. 1/2 would satisfy condition one but result in NO, but 2 would result in yes.
