NEW HERE? LEARN MORE
closeclose
It is currently 19 Apr 2024, 18:05
Register
GMAT Focus Tests
Decision Tracker
My Rewards
New posts
New comers' posts

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

What is the greatest common factor of positive integers x an

9 posts Go to First Unread Post
Print view
NEW TOPIC
POST REPLY
Question banks

GMAT Question Banks

Downloads
My Bookmarks
Reviews
SORT BY:
Date
Kudos
User avatar
enigma123
Senior Manager
Senior Manager
Joined: 25 Jun 2011
Status:Finally Done. Admitted in Kellogg for 2015 intake
Posts: 396
Location: United Kingdom
Concentration: International Business, Strategy
GMAT 1: 730 Q49 V45
GPA: 2.9
WE:Information Technology (Consulting)
What is the greatest common factor of positive integers x an [#permalink] New post  Updated on: 31 Dec 2013, 03:53
14
Bookmarks
00:00
A
B
C
D
E

Difficulty:

25% (medium)

Question Stats:

63% (00:51) correct 37% (00:55) wrong based on 424 sessions
Hide Show timer Statistics
What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor.
(2) x and y are unique prime numbers.

Below is my solution. Struggling to understand the official answer. Can someone please help?

Show Spoiler
Considering statement 1 : If X = 6 and Y = 9 then X = 2*3 and Y = 3 *3 and the GCF is 3 which is the common factor shared by both X and Y and of X = 4 and Y = 12 then X = 2^2 and Y = 2^2 * 3. Therefore the GCF is 4. Therefore this statement should be insufficient.

Considering statement 2 : If X = 2 and Y = 3, the GCF is 1 as this is the common factor shared by both.

Hence, I went for B, which is not the case.
ShowHide Answer
Official Answer
Official Answer and Stats are available only to registered users. Register/Login.

Originally posted by enigma123 on 31 Dec 2013, 02:41.
Last edited by Bunuel on 31 Dec 2013, 03:53, edited 3 times in total.
Renamed the topic and edited the question.
request expert reply
Most Helpful Reply
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92760
CAT Tests Forum Quiz Mode
Re: What is the greatest common factor of positive integers x an [#permalink] New post  31 Dec 2013, 03:55
3
Kudos
2
Bookmarks
Expert Reply
enigma123 wrote:
What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor.
(2) x and y are unique prime numbers.

Below is my solution. Struggling to understand the official answer. Can someone please help?

Show Spoiler
Considering statement 1 : If X = 6 and Y = 9 then X = 2*3 and Y = 3 *3 and the GCF is 3 which is the common factor shared by both X and Y and of X = 4 and Y = 12 then X = 2^2 and Y = 2^2 * 3. Therefore the GCF is 4. Therefore this statement should be insufficient.

Considering statement 2 : If X = 2 and Y = 3, the GCF is 1 as this is the common factor shared by both.

Hence, I went for B, which is not the case.


What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor --> every integer has 1 as a factor, thus since x and y share only one common factor it must be 1. Sufficient.

(2) x and y are unique prime numbers. Two different primes can have only 1 as common factor. Sufficient.

Answer: D.

Hope it's clear.
_________________
New to the GMAT CLUB Forum?

My Signature Questions' Collection:


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
General Discussion
avatar
unceldolan
Manager
Manager
Joined: 21 Oct 2013
Posts: 154
Location: Germany
Schools: Owen '17 (A$) Sauder '17 (A$) Schulich '17 (WD) Anderson FEMBA '17 (S) McDonough '17 (A) Desautels '17 (S)
GMAT 1: 660 Q45 V36
GPA: 3.51
Re: What is the greatest common factor of positive integers x an [#permalink] New post  18 Feb 2014, 04:33
Let's start with (2). A prime number is only divisible by 1 and itself. Hence the factors of a prime number are only 1 and itself. Now if you have two DIFFERENT unique prime numbers, the factor is 1.

Statement (1). At first I started as you, thought about types of numbers sharing common divisors/factors. Then I remembered that every number is also divisible by 1 and itself. Hence, the numbers mustn't share another factor than one. Hence the GCD would again be 1. Thus D is the correct answer.
User avatar
gmatprav
Manager
Manager
Joined: 25 Oct 2013
Posts: 115
Re: What is the greatest common factor of positive integers x an [#permalink] New post  06 Mar 2014, 05:45
Good question. Stmt 1 points that the common factor is 1 hence (1) is sufficient. Stmt 2 is also sufficient since two primes have 1 as the only common factor. D is the answer.
avatar
adityavb24
Intern
Intern
Joined: 18 Nov 2013
Posts: 2
Location: India
GPA: 3.64
WE:Brand Management (Retail)
Re: What is the greatest common factor of positive integers x an [#permalink] New post  11 Mar 2014, 04:18
Bunuel wrote:
enigma123 wrote:
What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor.
(2) x and y are unique prime numbers.

Below is my solution. Struggling to understand the official answer. Can someone please help?

Show Spoiler
Considering statement 1 : If X = 6 and Y = 9 then X = 2*3 and Y = 3 *3 and the GCF is 3 which is the common factor shared by both X and Y and of X = 4 and Y = 12 then X = 2^2 and Y = 2^2 * 3. Therefore the GCF is 4. Therefore this statement should be insufficient.

Considering statement 2 : If X = 2 and Y = 3, the GCF is 1 as this is the common factor shared by both.

Hence, I went for B, which is not the case.


What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor --> every integer has 1 as a factor, thus since x and y share only one common factor it must be 1. Sufficient.

(2) x and y are unique prime numbers. Two different primes can have only 1 as common factor. Sufficient.

Answer: D.

Hope it's clear.




(BUT) cant the two integers that is x and y be same??
thats y it should be C and not D
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92760
CAT Tests Forum Quiz Mode
Re: What is the greatest common factor of positive integers x an [#permalink] New post  11 Mar 2014, 04:31
Expert Reply
adityavb24 wrote:
Bunuel wrote:
enigma123 wrote:
What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor.
(2) x and y are unique prime numbers.

Below is my solution. Struggling to understand the official answer. Can someone please help?

Show Spoiler
Considering statement 1 : If X = 6 and Y = 9 then X = 2*3 and Y = 3 *3 and the GCF is 3 which is the common factor shared by both X and Y and of X = 4 and Y = 12 then X = 2^2 and Y = 2^2 * 3. Therefore the GCF is 4. Therefore this statement should be insufficient.

Considering statement 2 : If X = 2 and Y = 3, the GCF is 1 as this is the common factor shared by both.

Hence, I went for B, which is not the case.


What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor --> every integer has 1 as a factor, thus since x and y share only one common factor it must be 1. Sufficient.

(2) x and y are unique prime numbers. Two different primes can have only 1 as common factor. Sufficient.

Answer: D.

Hope it's clear.




(BUT) cant the two integers that is x and y be same??
thats y it should be C and not D


For (2) we are given that x and y are distinct: x and y are unique prime numbers.

As for (1): if x and y are the same number, say 3, then they would share all their factors 1 and 3, not just one.

The OA is correct.
_________________
New to the GMAT CLUB Forum?

My Signature Questions' Collection:


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics
Signature Read More
avatar
luckyme17187
Manager
Manager
Joined: 07 Apr 2014
Posts: 68
Re: What is the greatest common factor of positive integers x an [#permalink] New post  06 Sep 2014, 05:13
enigma123 wrote:
What is the greatest common factor of positive integers x and y?

(1) x and y share only one common factor.
(2) x and y are unique prime numbers.

Below is my solution. Struggling to understand the official answer. Can someone please help?

Show Spoiler
Considering statement 1 : If X = 6 and Y = 9 then X = 2*3 and Y = 3 *3 and the GCF is 3 which is the common factor shared by both X and Y and of X = 4 and Y = 12 then X = 2^2 and Y = 2^2 * 3. Therefore the GCF is 4. Therefore this statement should be insufficient.

Considering statement 2 : If X = 2 and Y = 3, the GCF is 1 as this is the common factor shared by both.

Hence, I went for B, which is not the case.




1. one is the factor for all the values. since both has only one common factor then it should be one. hence suff.

2. two rpime number shares only one as a common factor. hence suff.

Hence answer D.
User avatar
G
Temurkhon
Senior Manager
Senior Manager
Joined: 23 Jan 2013
Posts: 430
Schools: Cambridge'16
Re: What is the greatest common factor of positive integers x an [#permalink] New post  29 Nov 2016, 05:38
we are not asked to find X and Y, just GCF

St1. Share only one factor means that X and Y are coprime. No matter what number they are (5,6 or 2,3) GCF=1.Suff

St2. X and Y unique primes means again that hey are coprime, so GCF=1.Suff

D
User avatar
bumpbot
Non-Human User
Joined: 09 Sep 2013
Posts: 32545
Re: What is the greatest common factor of positive integers x an [#permalink] New post  08 Dec 2022, 03:17
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
Signature Read More
GMAT Club Bot
gmatclubot
Re: What is the greatest common factor of positive integers x an [#permalink]
08 Dec 2022, 03:17
NEW TOPIC
POST REPLY
Downloads
My Bookmarks
Reviews
Moderator:
Bunuel
Math Expert
92760 posts

cron

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions