If y is an integer, is y^3 divisible by 9? 1) y is divisible : GMAT Data Sufficiency (DS)
Check GMAT Club App Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 09 Dec 2016, 21:31

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If y is an integer, is y^3 divisible by 9? 1) y is divisible

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

### Hide Tags

Manager
Joined: 01 Sep 2003
Posts: 73
Location: NYC
Followers: 0

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

If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

03 Jan 2004, 21:38
1
This post was
BOOKMARKED
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 10 sessions

### HideShow timer Statistics

If y is an integer, is y^3 divisible by 9?

1) y is divisible by 4

2) y is divisible by 6

>>>>>>>>>>>> Answer is B ...why?? >>>>>>>>.
Director
Joined: 13 Nov 2003
Posts: 964
Location: Florida
Followers: 1

Kudos [?]: 118 [0], given: 0

[#permalink]

### Show Tags

03 Jan 2004, 22:26
factorize 6: 2 and 3
Y^3 will be (2*3)^3 = 2^3 * 3^3
3^3 will always be divisible by 9

thus, B
Intern
Joined: 24 May 2011
Posts: 22
Followers: 0

Kudos [?]: 6 [1] , given: 5

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

02 Dec 2011, 20:21
1
This post received
KUDOS
I'm a bit confused here.
The question does not suggest that y is not 0.
y = 0 satisfies both, y is divisible by 4 and y is divisible by 6.
In that case we can say that y^3 is divisible by 9 and that D is the answer.
Is it not correct?
Retired Moderator
Status: 2000 posts! I don't know whether I should feel great or sad about it! LOL
Joined: 04 Oct 2009
Posts: 1712
Location: Peru
Schools: Harvard, Stanford, Wharton, MIT & HKS (Government)
WE 1: Economic research
WE 2: Banking
WE 3: Government: Foreign Trade and SMEs
Followers: 95

Kudos [?]: 888 [0], given: 109

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

02 Dec 2011, 21:59
shm0401 wrote:
I'm a bit confused here.
The question does not suggest that y is not 0.
y = 0 satisfies both, y is divisible by 4 and y is divisible by 6.
In that case we can say that y^3 is divisible by 9 and that D is the answer.
Is it not correct?

You are right. The question should mention that Y cannot be 0 or that Y is a positive integer.
If I read that question in the real test, I would assume that Y can be 0 too.

Kudos to you!
_________________

"Life’s battle doesn’t always go to stronger or faster men; but sooner or later the man who wins is the one who thinks he can."

My Integrated Reasoning Logbook / Diary: http://gmatclub.com/forum/my-ir-logbook-diary-133264.html

GMAT Club Premium Membership - big benefits and savings

GMAT Tutor
Joined: 24 Jun 2008
Posts: 1183
Followers: 409

Kudos [?]: 1480 [0], given: 4

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

03 Dec 2011, 16:41
metallicafan wrote:
shm0401 wrote:
I'm a bit confused here.
The question does not suggest that y is not 0.
y = 0 satisfies both, y is divisible by 4 and y is divisible by 6.
In that case we can say that y^3 is divisible by 9 and that D is the answer.
Is it not correct?

You are right. The question should mention that Y cannot be 0 or that Y is a positive integer.
If I read that question in the real test, I would assume that Y can be 0 too.

Kudos to you!

While on the real GMAT, divisibility questions are always restricted to positive integers only, it doesn't actually make any difference to the answer here if you allow y to be zero. Statement 1 is still not sufficient (y might be 0 or 12, in which case y^3 is divisible by 9, or y might be 4 or 8, in which case y^3 is not divisible by 9), and Statement 2 is still sufficient, since y^3 must be divisible by 9 even if y=0 (since 0 is divisible by every positive integer).
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Manager
Joined: 11 May 2009
Posts: 126
Schools: Columbia Business School, Goizueta, Sloan
Followers: 3

Kudos [?]: 3 [0], given: 28

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

04 Dec 2011, 03:04
The technique that Manhattan GMAT guides use make D-S questions easier. The key lies in paraphrasing the question and then paraphrasing the statements. It would be like this:

Question: What integer is y if (y^3)/9 = integer?

1) y is 4 or divisible by 4. y^3 = 4*4*4 = 64; 64/9 = 7.111 thus y is not an integer

2) y is 6 or divisible by 6. 6^3 = 6*6*6 = 216; 216/9 = 24 thus y is an integer

the correct answer is B.

There is also more accurate approach which could save you time if you know how to use it well. Since you know the value of y, you can use prime factorization to find the solution.

1) y is 4. prime factors are 2*2. y^3 = 2*2*2*2*2*2 the six twos are never divisible by 9, because prime factors of 9 are 3*3

2) y is 6. prime factors are 2*3. y^3 = 2*3*2*3*2*3 or 2^3*3^3. since y^3 has three 3's it must be divisible by two 3's

Correct answer is B.

Hope it helps
_________________

Set your aims high, carpe diem

Intern
Joined: 24 May 2011
Posts: 22
Followers: 0

Kudos [?]: 6 [0], given: 5

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

04 Dec 2011, 09:17
metallicafan, IanStewart, Laker7 , thank you for your answers.
It has helped me understand the way i have to look at the problem.
Forum Moderator
Status: mission completed!
Joined: 02 Jul 2009
Posts: 1426
GPA: 3.77
Followers: 180

Kudos [?]: 844 [0], given: 621

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

04 Dec 2011, 20:56
for 1) try 12 - yes divisible, try 4- not divisible
for 2) any number divisible by 6 is a multiple of 3, and 3^3 is 9 which is divisibe by 9.
_________________

Audaces fortuna juvat!

GMAT Club Premium Membership - big benefits and savings

Manager
Joined: 30 Sep 2009
Posts: 124
Followers: 0

Kudos [?]: 27 [0], given: 183

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

04 Dec 2011, 21:04
If y=0 for option 1 then y is divisible by 9....

But if y=8 then y is not divisible by 9...

So there are lots of possiblities there so we have to rule out the possibility of option A.
Manager
Joined: 24 Oct 2011
Posts: 95
Location: India
Concentration: General Management, International Business
GMAT Date: 11-29-2011
GPA: 3.5
WE: Web Development (Computer Software)
Followers: 1

Kudos [?]: 16 [1] , given: 27

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

04 Dec 2011, 21:26
1
This post received
KUDOS
Simple.. In option B, we have 6 which is multiple of 3. So obviously any number div by 3 - the number cube is obviously div by 3.
Manager
Status: Essaying
Joined: 27 May 2010
Posts: 153
Location: Ghana
Concentration: Finance, Finance
Schools: Cambridge
GMAT 1: 690 Q47 V37
GPA: 3.9
WE: Accounting (Education)
Followers: 1

Kudos [?]: 9 [0], given: 8

Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible [#permalink]

### Show Tags

05 Dec 2011, 04:34
I went with B because 6 has 2 and 3 as factors. so Y has 3 as a factor. therefore Y cube has at least 3 3s as a factor. So 9 which has only 2 3s can divide it
Re: If y is an integer, is y^3 divisible by 9? 1) y is divisible   [#permalink] 05 Dec 2011, 04:34
Similar topics Replies Last post
Similar
Topics:
10 If y is an integer, is y^3 divisible by 9 ? 7 29 Jan 2014, 01:18
4 If y is an integer, is y^3 divisible by 8? 4 16 Sep 2012, 08:45
2 If y is an integer is y^3 divisible by 9 10 24 May 2011, 06:07
1 If y is an integer, is y^3 divisible by 9? 9 08 Jul 2011, 01:04
31 Is x^2*y^4 an integer divisible by 9 ? 19 13 Sep 2010, 13:15
Display posts from previous: Sort by

# If y is an integer, is y^3 divisible by 9? 1) y is divisible

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

 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®.