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

It is currently 22 Jul 2014, 15:48

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

gcf and lcm problem

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Manager
Manager
avatar
Joined: 28 Jun 2008
Posts: 50
Followers: 0

Kudos [?]: 4 [0], given: 31

gcf and lcm problem [#permalink] New post 04 Jun 2009, 20:41
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

100% (02:18) correct 0% (00:00) wrong based on 2 sessions
hey guys was wondering if someone could offer a way to solve this problem:



If X and Y are integers, what is the value of xy?

(1) The greates common factor of X and Y is 10

(2) The least common multiple of X and Y is 180

ANSWER: C.
1 KUDOS received
Director
Director
avatar
Joined: 23 May 2008
Posts: 840
Followers: 3

Kudos [?]: 25 [1] , given: 0

GMAT Tests User
Re: gcf and lcm problem [#permalink] New post 04 Jun 2009, 23:56
1
This post received
KUDOS
scorpio7 wrote:
hey guys was wondering if someone could offer a way to solve this problem:



If X and Y are integers, what is the value of xy?

(1) The greates common factor of X and Y is 10

(2) The least common multiple of X and Y is 180

ANSWER: C.


E

1) x and y could be a variety of numbers that include the primes 2 and 5
insuff
2) x and y could be a variety of numbers with prime factors that include 3,3,5,2,2 between the two

together
x and y must both contain 2 and 5, but there is only one 5 in 180
insufficient
Senior Manager
Senior Manager
User avatar
Joined: 16 Jan 2009
Posts: 362
Concentration: Technology, Marketing
GMAT 1: 700 Q50 V34
GPA: 3
WE: Sales (Telecommunications)
Followers: 2

Kudos [?]: 65 [0], given: 16

GMAT Tests User
Re: gcf and lcm problem [#permalink] New post 05 Jun 2009, 01:41
1)
x and y could be 20 ,30/30,40......any number with 2,5 as factors
insufficient

2)
x and y could be a variety of numbers with prime factors that include 3,3,5,2,2
iNSUFFIENT

TOGETHER

x and y must have 2,5 as factors ; however the remaining factors can be adjusted in many ways

iNSUFFIENT
IMO E

_________________

Lahoosaher

2 KUDOS received
Manager
Manager
avatar
Joined: 12 Apr 2006
Posts: 220
Location: India
Followers: 1

Kudos [?]: 18 [2] , given: 17

GMAT Tests User
Re: gcf and lcm problem [#permalink] New post 05 Jun 2009, 02:41
2
This post received
KUDOS
bigtreezl wrote:
E

1) x and y could be a variety of numbers that include the primes 2 and 5
insuff
2) x and y could be a variety of numbers with prime factors that include 3,3,5,2,2 between the two

together
x and y must both contain 2 and 5, but there is only one 5 in 180
insufficient

I think we can find the value of XY

Statement (1) says 2 and 5 are common factors of X and Y-------Insufficient
Statement (2) the LCM of X and Y is 180 which means 2,2,3,3, and 5 factors of X and Y-------Insufficient

Combining both the statements

2 5 2 3 3
2 5
-------------------------------------------------
GCF 2 x 5 = 10 (Greatest power of common multiples)
LCM 2 x 5 x 2 x 3 x 3 = 180 (Least power of all the multiples)

The only common primes between X and Y are 5, and 2. The remaining primes of LCM (2, 3, 3) will be primes of either X or Y and not both, because if it will be in both it will be multiplied to get the GCF.

The number in this case would be 180*10 = 1800. Hence C is the answer

Some good info on LCM and GCF http://www.purplemath.com/modules/lcm_gcf.htm
1 KUDOS received
Manager
Manager
avatar
Joined: 04 Dec 2008
Posts: 113
Followers: 1

Kudos [?]: 36 [1] , given: 2

Re: gcf and lcm problem [#permalink] New post 05 Jun 2009, 05:07
1
This post received
KUDOS
humans wrote:
bigtreezl wrote:
E

1) x and y could be a variety of numbers that include the primes 2 and 5
insuff
2) x and y could be a variety of numbers with prime factors that include 3,3,5,2,2 between the two

together
x and y must both contain 2 and 5, but there is only one 5 in 180
insufficient

I think we can find the value of XY

Statement (1) says 2 and 5 are common factors of X and Y-------Insufficient
Statement (2) the LCM of X and Y is 180 which means 2,2,3,3, and 5 factors of X and Y-------Insufficient

Combining both the statements

2 5 2 3 3
2 5
-------------------------------------------------
GCF 2 x 5 = 10 (Greatest power of common multiples)
LCM 2 x 5 x 2 x 3 x 3 = 180 (Least power of all the multiples)

The only common primes between X and Y are 5, and 2. The remaining primes of LCM (2, 3, 3) will be primes of either X or Y and not both, because if it will be in both it will be multiplied to get the GCF.

The number in this case would be 180*10 = 1800. Hence C is the answer

Some good info on LCM and GCF http://www.purplemath.com/modules/lcm_gcf.htm


I agree. One of the properties of GCF and LCM is (GCF of A and B) * (LCM of A and B) = A*B.
GCF consist of shared prime factors and LCM consist of non-shared prime factors. Together they both form the combined integer as demonstrated by humans.

Answer is definitely C.
1 KUDOS received
Manager
Manager
avatar
Joined: 15 Apr 2008
Posts: 169
Followers: 2

Kudos [?]: 10 [1] , given: 1

GMAT Tests User
Re: gcf and lcm problem [#permalink] New post 05 Jun 2009, 08:58
1
This post received
KUDOS
the answer should be C.
the product of 2 number= product of their Lcm and HCF
1 KUDOS received
Director
Director
avatar
Joined: 23 May 2008
Posts: 840
Followers: 3

Kudos [?]: 25 [1] , given: 0

GMAT Tests User
Re: gcf and lcm problem [#permalink] New post 05 Jun 2009, 22:39
1
This post received
KUDOS
humans wrote:
bigtreezl wrote:
E

1) x and y could be a variety of numbers that include the primes 2 and 5
insuff
2) x and y could be a variety of numbers with prime factors that include 3,3,5,2,2 between the two

together
x and y must both contain 2 and 5, but there is only one 5 in 180
insufficient

I think we can find the value of XY

Statement (1) says 2 and 5 are common factors of X and Y-------Insufficient
Statement (2) the LCM of X and Y is 180 which means 2,2,3,3, and 5 factors of X and Y-------Insufficient

Combining both the statements

2 5 2 3 3
2 5
-------------------------------------------------
GCF 2 x 5 = 10 (Greatest power of common multiples)
LCM 2 x 5 x 2 x 3 x 3 = 180 (Least power of all the multiples)

The only common primes between X and Y are 5, and 2. The remaining primes of LCM (2, 3, 3) will be primes of either X or Y and not both, because if it will be in both it will be multiplied to get the GCF.

The number in this case would be 180*10 = 1800. Hence C is the answer

Some good info on LCM and GCF http://www.purplemath.com/modules/lcm_gcf.htm


yeah..you're right..makes perfect sense
Re: gcf and lcm problem   [#permalink] 05 Jun 2009, 22:39
    Similar topics Author Replies Last post
Similar
Topics:
4 Experts publish their posts in the topic The LCM of three numbers is four times their GCF. Which of emmak 8 11 Mar 2013, 23:36
1 Experts publish their posts in the topic Having issues with finding LCM and GCF, can someone help? DelSingh 3 09 Feb 2013, 10:07
GCF TomB 4 01 May 2011, 01:44
Ok, for some reason these GCF/LCM, etc. problems get me... raconteur 7 11 Apr 2007, 22:59
GCF and LCM manhattanbrent 1 01 Feb 2007, 14:40
Display posts from previous: Sort by

gcf and lcm problem

  Question banks Downloads My Bookmarks Reviews Important topics  


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®.