It is currently 25 Jun 2017, 21:11

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

Events & Promotions in June
Open Detailed Calendar

If x > y, is zx > yx?

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

Hide Tags

Intern
Intern
avatar
Joined: 23 Jul 2012
Posts: 5
Concentration: Finance, Strategy
GMAT 1: 560 Q37 V28
GPA: 3.75
WE: Accounting (Accounting)
If x > y, is zx > yx? [#permalink]

Show Tags

New post 30 Jul 2012, 19:13
4
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

62% (02:27) correct 38% (01:08) wrong based on 208 sessions

HideShow timer Statistics

If x > y, is zx > yx?

(1) z > 0

(2) y < 0
[Reveal] Spoiler: OA
Expert Post
5 KUDOS received
Math Expert
User avatar
D
Joined: 02 Sep 2009
Posts: 39673
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 31 Jul 2012, 01:13
5
This post received
KUDOS
Expert's post
2
This post was
BOOKMARKED
If x > y, is zx > yx?

Is \(zx > yx\)? --> is \(zx-yx>0\)? --> is \(x(z-y) >0\)?

(1) z > 0. Clearly insufficient.

(2) y < 0. Clearly insufficient.

(1)+(2) Now, remember that we can subtract inequalities with the signs in opposite direction --> subtract (2) from (1): \(z-y>0\). So, we know that the second multiply in \(x(z-y)\) is positive, but we still don't know the sign of \(x\): from the stem (\(x>y\)) and the second statement (\(y<0\)) the only thing we can deduce is that \(x\) is greater than negative number \(y\), hence \(x\) could be negative, positive or zero. Not sufficient.

Answer: E.

Hope it's clear.
_________________

New to the Math Forum?
Please read this: All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Senior Manager
Senior Manager
avatar
Joined: 06 Aug 2011
Posts: 400
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 31 Jul 2012, 02:03
Its E.. bt i got c ..then i realized we must knw what wud be the value of x ..and value of x is not given ...so its E..
_________________

Bole So Nehal.. Sat Siri Akal.. Waheguru ji help me to get 700+ score !

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 15980
Premium Member
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 12 Dec 2013, 03:10
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Intern
Intern
avatar
Joined: 26 May 2012
Posts: 49
Concentration: Marketing, Statistics
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 23 Dec 2013, 19:57
Does anyone have advice on how to tackle these problems faster? I always end up resorting to plugging in numbers and various conditions and even though that helps me ensure more accuracy, it usually takes me about 3 min. per such problem (inequalities with only variables).
GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 15980
Premium Member
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 07 Jul 2015, 09:51
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Director
Director
User avatar
S
Joined: 23 Jan 2013
Posts: 585
Schools: Cambridge'16
If x > y, is zx > yx? [#permalink]

Show Tags

New post 15 Sep 2015, 02:23
x>y and Is zx>yx? Y/N question

The question: Is z>x and x,y,z>0?

St.1 z>0. INSUFF (we do not know whether x,y>0)
St.2 y<0. INSUFF (we do not need other variables because if one is negative we cannot answer definitely)
St.1+St.2. Still y<0, so INSUFF

E
Intern
Intern
avatar
Joined: 31 Mar 2014
Posts: 8
If x > y, is zx > yx? [#permalink]

Show Tags

New post 24 Sep 2015, 11:19
just to make sure i understood it:
zx > yx --> we cannot simplify to z > y because we don't know if x is positive or negative, right?
Expert Post
1 KUDOS received
Math Forum Moderator
avatar
B
Joined: 20 Mar 2014
Posts: 2643
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44
GPA: 3.7
WE: Engineering (Aerospace and Defense)
GMAT ToolKit User Premium Member Reviews Badge
If x > y, is zx > yx? [#permalink]

Show Tags

New post 24 Sep 2015, 11:43
1
This post received
KUDOS
Expert's post
1
This post was
BOOKMARKED
nicksson wrote:
just to make sure i understood it:
zx > yx --> we cannot simplify to z > y because we don't know if x is positive or negative, right?


Yes exactly. In inequalities be very careful with cancelling variables without knowing for sure what signs are they.

In the current question, zx>xy --> x(z-y)>0

After combining the 2 statements, you do know that -y>0 and z>0 ---> z-y>0 but without knowing the sign of 'x', you will not be able to answer yes or no for the question asked.

Hope this helps.
_________________

Thursday with Ron updated list as of July 1st, 2015: http://gmatclub.com/forum/consolidated-thursday-with-ron-list-for-all-the-sections-201006.html#p1544515
Rules for Posting in Quant Forums: http://gmatclub.com/forum/rules-for-posting-please-read-this-before-posting-133935.html
Writing Mathematical Formulae in your posts: http://gmatclub.com/forum/rules-for-posting-please-read-this-before-posting-133935.html#p1096628
GMATCLUB Math Book: http://gmatclub.com/forum/gmat-math-book-in-downloadable-pdf-format-130609.html
Everything Related to Inequalities: http://gmatclub.com/forum/inequalities-made-easy-206653.html#p1582891
Inequalities tips: http://gmatclub.com/forum/inequalities-tips-and-hints-175001.html
Debrief, 650 to 750: http://gmatclub.com/forum/650-to-750-a-10-month-journey-to-the-score-203190.html

GMAT Club Legend
GMAT Club Legend
User avatar
Joined: 09 Sep 2013
Posts: 15980
Premium Member
Re: If x > y, is zx > yx? [#permalink]

Show Tags

New post 20 Oct 2016, 04:19
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: If x > y, is zx > yx?   [#permalink] 20 Oct 2016, 04:19
    Similar topics Author Replies Last post
Similar
Topics:
7 Experts publish their posts in the topic If xy ≠ 0, is a > y/x? Bunuel 8 06 Nov 2016, 13:36
7 Experts publish their posts in the topic If x and y cannot be equal to zero, is x/y > y/x ? Bunuel 9 29 Oct 2016, 01:33
5 Experts publish their posts in the topic Is x < y ? (1) y/x > x/y (2) y > 100 goodyear2013 4 23 Mar 2017, 02:52
26 Experts publish their posts in the topic If y=|x+1|/x and x!=0, is xy>0? Zarrolou 11 08 Sep 2016, 04:51
If x and y are prime numbers, is y(x-3) odd? (1) x> 10 MitDavidDv 5 04 Apr 2011, 17:02
Display posts from previous: Sort by

If x > y, is zx > yx?

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


cron

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

Powered by phpBB © phpBB Group and phpBB SEO

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®.