GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 17 Jan 2019, 22:05

Close

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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
  • The winning strategy for a high GRE score

     January 17, 2019

     January 17, 2019

     08:00 AM PST

     09:00 AM PST

    Learn the winning strategy for a high GRE score — what do people who reach a high score do differently? We're going to share insights, tips and strategies from data we've collected from over 50,000 students who used examPAL.
  • Free GMAT Strategy Webinar

     January 19, 2019

     January 19, 2019

     07:00 AM PST

     09:00 AM PST

    Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

If xy>0, is x^3y^4>0?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6811
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
If xy>0, is x^3y^4>0?  [#permalink]

Show Tags

New post 22 Jan 2018, 00:03
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

59% (00:50) correct 41% (00:29) wrong based on 53 sessions

HideShow timer Statistics

[GMAT math practice question]

If \(xy>0\), is \(x^3y^4>0?\)

\(1) x>0\)
\(2) y>0\)

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Retired Moderator
avatar
D
Joined: 25 Feb 2013
Posts: 1220
Location: India
GPA: 3.82
GMAT ToolKit User Premium Member Reviews Badge
Re: If xy>0, is x^3y^4>0?  [#permalink]

Show Tags

New post 22 Jan 2018, 09:00
MathRevolution wrote:
[GMAT math practice question]

If \(xy>0\), is \(x^3y^4>0?\)

\(1) x>0\)
\(2) y>0\)


\(x^3y^4>0=>y(xy)^3>0\) as \(xy>0=>(xy)^3>0\). Hence we need to know Is \(y>0\)?

Statement 1: \(x>0\) and we know \(xy>0\) so \(y>0\). Sufficient

Statement 2: directly provides \(y>0\). Sufficient

Option D
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6811
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: If xy>0, is x^3y^4>0?  [#permalink]

Show Tags

New post 24 Jan 2018, 00:24
=>

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.

Modifying the question:
\(x^3y^4>0\)
\(⇔ x>0\)
since \(y^4>0\) is always true. We can ignore even exponents in inequalities that have \(0\) on one side.
So, the question becomes, ‘is \(x>0\)?’.

Condition 1) is certainly sufficient.

Condition 2):
\(x > 0\) since \(y > 0\) and \(xy > 0\). Thus, condition 2) is also sufficient.

Therefore, D is the answer.

Note: Tip 1) of the VA method states that D is most likely to be the answer if condition 1) gives the same information as condition 2).

Answer: D
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $149 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

GMAT Club Bot
Re: If xy>0, is x^3y^4>0? &nbs [#permalink] 24 Jan 2018, 00:24
Display posts from previous: Sort by

If xy>0, is x^3y^4>0?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.