Find all School-related info fast with the new School-Specific MBA Forum

It is currently 24 Apr 2014, 03:19

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If x and y are both integers greater than 1, is x a multiple

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Senior Manager
Senior Manager
User avatar
Joined: 24 Feb 2008
Posts: 349
Schools: UCSD ($) , UCLA, USC ($), Stanford
Followers: 108

Kudos [?]: 1039 [0], given: 2

GMAT Tests User
If x and y are both integers greater than 1, is x a multiple [#permalink] New post 04 May 2008, 18:26
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

76% (01:47) correct 23% (01:31) wrong based on 42 sessions
If x and y are both integers greater than 1, is x a multiple of y?

(1) 3y^2 + 7y = x
(2) x^2 -x is a multiple of y
[Reveal] Spoiler: OA

_________________

Chinese Democracy is misunderstood...at your nearest BestBuy.

Best AWA guide here: how-to-get-6-0-awa-my-guide-64327.html

SVP
SVP
Joined: 04 May 2006
Posts: 1943
Schools: CBS, Kellogg
Followers: 14

Kudos [?]: 212 [0], given: 1

Premium Member CAT Tests
Re: DS: x multiple of y? [#permalink] New post 04 May 2008, 19:35
chineseburned wrote:
If x and y are both integers greater than 1, is x a multiple of y?

(1) 3y^2 + 7y = x
(2) x^2 -x is a multiple of y


Hi, it is long time to see you!

1 suff. no discustion
2. x(x-1) is multiple of y. So x may or may not is multiple of y.

a. x=5, y = 2
5*6 is multiple of 2, but x=5 is not multiple of 2

b. x=6
6*7 is multiple of 2, and x=6 is multiple of 2
VP
VP
Joined: 10 Jun 2007
Posts: 1469
Followers: 5

Kudos [?]: 87 [0], given: 0

GMAT Tests User
Re: DS: x multiple of y? [#permalink] New post 04 May 2008, 19:55
chineseburned wrote:
If x and y are both integers greater than 1, is x a multiple of y?

(1) 3y^2 + 7y = x
(2) x^2 -x is a multiple of y


A.

Given:
x > 1
y > 1
n, x, y = integer
Asking: Is x = ny?

(1) x = y*(3y + 7)
Because y is integer, (3y + 7) must be integer; therefore, x must equal integer * y
SUFFICIENT

(2) x^2 - x = ny
Plug in numbers to satisfy above condition...
Say x=3, n=1, then y=6. In this case, x is not a multiple of y.
Say x=6, n=15, then y=2. In this case, x is a multiple of y.
The solution actually depends on what n is, and the only condition we have is n is integer. Therefore, it is INSUFFICIENT
CEO
CEO
User avatar
Joined: 29 Aug 2007
Posts: 2504
Followers: 48

Kudos [?]: 452 [0], given: 19

GMAT Tests User
Re: DS: x multiple of y? [#permalink] New post 04 May 2008, 20:29
chineseburned wrote:
If x and y are both integers greater than 1, is x a multiple of y?

(1) 3y^2 + 7y = x
(2) x^2 -x is a multiple of y



(1) 3y^2 + 7y = x
y (3y + 7) = x
so x must be a multiple, (3y+7) times, of y. suff...

(2) x^2 -x is a multiple of y
x^2 - x = yk where k is an integer.
x (x-1) = yk
from this we do not know whether x - 1 or x is equal to k. so nsf....

A.
_________________

Verbal: new-to-the-verbal-forum-please-read-this-first-77546.html
Math: new-to-the-math-forum-please-read-this-first-77764.html
Gmat: everything-you-need-to-prepare-for-the-gmat-revised-77983.html


GT

Intern
Intern
Joined: 08 Apr 2008
Posts: 47
Followers: 0

Kudos [?]: 6 [0], given: 0

Re: DS: x multiple of y? [#permalink] New post 24 Jun 2008, 17:02
GMAT TIGER wrote:

(2) x^2 -x is a multiple of y
x^2 - x = yk where k is an integer.
x (x-1) = yk
from this we do not know whether x - 1 or x is equal to k. so nsf....


What is the reasoning behind multiplying y by another variable in Statement 2 (in this case k)?
Director
Director
Joined: 14 Aug 2007
Posts: 736
Followers: 7

Kudos [?]: 89 [0], given: 0

GMAT Tests User
Re: DS: x multiple of y? [#permalink] New post 24 Jun 2008, 22:26
AlinderPatel wrote:
GMAT TIGER wrote:

(2) x^2 -x is a multiple of y
x^2 - x = yk where k is an integer.
x (x-1) = yk
from this we do not know whether x - 1 or x is equal to k. so nsf....


What is the reasoning behind multiplying y by another variable in Statement 2 (in this case k)?


2)x^2 -x is a multiple of y

let K be the multiple.

then x^2-x = K . y

Hope this helps
Intern
Intern
Joined: 10 Jun 2010
Posts: 3
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: DS: x multiple of y? [#permalink] New post 10 Jun 2010, 06:41
so if we have

y^2-y = X

Then we could say with certitude that X is a multiple of Y?
Manager
Manager
Joined: 02 May 2010
Posts: 56
Schools: IU, UT Dallas, Univ of Georgia, Univ of Arkansas, Miami University
WE 1: 5.5 Yrs IT
Followers: 1

Kudos [?]: 2 [0], given: 3

Re: DS: x multiple of y? [#permalink] New post 10 Jun 2010, 06:54
Yes. If it was given that y^2-y = x, then x is certainly a multiple of y.

y^2-y = x
y(y-1) = x
y*k = x
Intern
Intern
User avatar
Joined: 16 Jul 2010
Posts: 18
Followers: 1

Kudos [?]: 7 [0], given: 9

Re: DS: x multiple of y? [#permalink] New post 17 Jul 2010, 06:52
So from x(x-1)=yk, can we not derive:

x=y*k/(x-1)=yk?

In which case the answer is C, not A.
_________________

If you find my posts useful, please award me some Kudos!

1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 17394
Followers: 2889

Kudos [?]: 18492 [1] , given: 2361

GMAT Tests User CAT Tests
Re: DS: x multiple of y? [#permalink] New post 17 Jul 2010, 07:12
1
This post received
KUDOS
Expert's post
dauntingmcgee wrote:
So from x(x-1)=yk, can we not derive:

x=y*k/(x-1)=yk?

In which case the answer is C, not A.


We don't know whether \frac{k}{x-1} is an integer, hence we can not write x=yn (where n is an integer) from x(x-1)=yk.

If x and y are integers great than 1, is x a multiple of y?

Is x=ny, where n=integer\geq{1}?

(1) 3y^2+7y=x --> y(3y+7)=x --> as 3y+7=integer, then y*integer=x --> x is a multiple of y. Sufficient.

(2) x^2-x is a multiple of y --> x^2-x=my --> x(x-1)=my --> x can be multiple of y (x=2 and y=2) OR x-1 can be multiple of y (x=3 and y=2) or their product can be multiple of y (x=3 and y=6). Not sufficient.

Answer: A.

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

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?
25 extra-hard Quant Tests

Intern
Intern
User avatar
Joined: 16 Jul 2010
Posts: 18
Followers: 1

Kudos [?]: 7 [0], given: 9

Re: DS: x multiple of y? [#permalink] New post 17 Jul 2010, 09:46
Yes, that is great. Thank you. Guess I'm a little rustier than I thought.
_________________

If you find my posts useful, please award me some Kudos!

Re: DS: x multiple of y?   [#permalink] 17 Jul 2010, 09:46
    Similar topics Author Replies Last post
Similar
Topics:
This topic is locked, you cannot edit posts or make further replies. New 2 If x and y are integers greater than 1, is x a multiple of themagiccarpet 45 16 Nov 2005, 01:56
New posts if x and y are integrs greater than 1, is x a multiple of y deep 3 15 Nov 2006, 00:45
Popular new posts If x and y are integers greater than 1, is x a multiple of asaf 13 22 Jul 2007, 20:18
New posts If x an y are integers greater than 1, is x a multiple of y? mba9now 3 29 Jul 2008, 20:10
Popular new posts 17 Experts publish their posts in the topic If x and y are integers greater than 1, is x a multiple of y enigma123 11 29 Jan 2012, 15:21
Display posts from previous: Sort by

If x and y are both integers greater than 1, is x a multiple

  Question banks Downloads My Bookmarks Reviews Important topics  


cron

GMAT Club MBA Forum Home| About| Privacy Policy| 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®.