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

 It is currently 21 May 2013, 09:00

# Is x and y are positive integers, what is the value of xy?

Author Message
TAGS:
Manager
Joined: 24 Apr 2008
Posts: 56
Followers: 1

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

Is x and y are positive integers, what is the value of xy? [#permalink]  26 Apr 2008, 08:24
00:00

Question Stats:

9% (02:52) correct 90% (00:56) wrong based on 0 sessions
Is x and y are positive integers, what is the value of xy?

(i) The greatest common factor of x and y is 10
(ii) The least common multiple of x and y is 180
SVP
Joined: 04 May 2006
Posts: 1946
Schools: CBS, Kellogg
Followers: 10

Kudos [?]: 168 [1] , given: 1

Re: DS - greatest common factor and least common multiple [#permalink]  27 Apr 2008, 19:17
1
KUDOS
jimmyjamesdonkey wrote:
anyway to solve this in under 2mins? fresh?

Yes, even under 20 seconds if you remember that xy = GCD*LCM. Sure!
_________________
Current Student
Joined: 28 Dec 2004
Posts: 3439
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 11

Kudos [?]: 134 [0], given: 2

Re: DS - greatest common factor and least common multiple [#permalink]  26 Apr 2008, 08:55
quiet888 wrote:
Is x and y are positive integers, what is the value of xy?

(i) The greatest common factor of x and y is 10
(ii) The least common multiple of x and y is 180

these question ans choice is always either C or E..

lets see..

xy?
1)
gcd is 10

x=10 y=20
GCD =10 xy=200
x=10 y=60
GCD=10, xy=600

2)
LCM
x=180 y=2 LCM=180 xy=360
x=180 y=180 LCM=180 xy=180^2
Insuf

together
suppose x=180 y=10

suppse x=90 y=20

xy= is the same..Sufficient C it is.
Current Student
Joined: 28 Dec 2004
Posts: 3439
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 11

Kudos [?]: 134 [0], given: 2

Re: DS - greatest common factor and least common multiple [#permalink]  26 Apr 2008, 11:50
another thing..with these type of question where we have the GCD and LCM..usually we can tell something like an XY but we cant really tell what X is or what y is...
Director
Joined: 01 May 2007
Posts: 809
Followers: 1

Kudos [?]: 37 [0], given: 0

Re: DS - greatest common factor and least common multiple [#permalink]  27 Apr 2008, 14:27
anyway to solve this in under 2mins? fresh?
Director
Joined: 01 May 2007
Posts: 809
Followers: 1

Kudos [?]: 37 [0], given: 0

Re: DS - greatest common factor and least common multiple [#permalink]  28 Apr 2008, 07:25
Woah can you elaborate that a little bit...I always have such problems with GCF & LCM..
Intern
Joined: 29 Jun 2011
Posts: 37
Followers: 0

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

Re: DS - greatest common factor and least common multiple [#permalink]  19 Jul 2011, 00:30
FN wrote:
quiet888 wrote:
Is x and y are positive integers, what is the value of xy?

(i) The greatest common factor of x and y is 10
(ii) The least common multiple of x and y is 180

these question ans choice is always either C or E..

lets see..

xy?
1)
gcd is 10

x=10 y=20
GCD =10 xy=200
x=10 y=60
GCD=10, xy=600

2)
LCM
x=180 y=2 LCM=180 xy=360
x=180 y=180 LCM=180 xy=180^2
Insuf

together
suppose x=180 y=10

suppse x=90 y=20

xy= is the same..Sufficient C it is.

hi, For (ii) The least common multiple of x and y is 180
isn't x*y = 5400?

my rational...

if 180 is the Lowest Common Multiple, meaning that both x and y have 3, 3, 5, 2, 2 at least appeared twice for x y.

So if

x = 2, ?, 3, 5
y = 2, ?, 3, 5
-------------
x & y's LCM which is 180 = 2* 3* 5* ?* ?*

So after pulling 5 & 3 & 2, we still need one 2 and one 3 to fulfil the 3, 3, 5, 2, 2 = (180) requirement. Having said that, the ? in each x & y should be 2 and 3.

So multiple all 8 digits, it should x*y = 2* 2* 3* 5* 2* 3*3* 5* = 5400?
Manager
Joined: 07 Jun 2011
Posts: 83
Followers: 0

Kudos [?]: 9 [0], given: 31

Re: DS - greatest common factor and least common multiple [#permalink]  01 Aug 2011, 08:31
Could some body help me to understand this a little better.

here is where I am getting stuck

GCF = 10, There for X = 10A nd Y = 10B where A and B are separate constants

for example 20 and 30, here the GDF is 10 and a = 2 and b = 3

sice we dont have a and b from this equation. this is insufficient

statement 2:

LCM is 180
so X*N1 = 180 and Y * N2 = 180

since we do not know the values of N1 and N2 this statement is not sufficient.

even if we combine, we dont have information to solve.

I see come body explaining the answer are LCM*GCD. Could you please tell me how you arrived at that equation
Manager
Status: Trying to survive
Joined: 29 Jun 2011
Posts: 190
GMAt Status: Quant section
Concentration: Finance, Real Estate
Schools: WBS (D)
GMAT Date: 12-30-2011
GPA: 3.2
Followers: 9

Kudos [?]: 79 [0], given: 94

Re: DS - greatest common factor and least common multiple [#permalink]  01 Aug 2011, 09:38
GCF * LCM = X*Y it's a general rule
10*180 = 1800
so the the answer is C and u need less than 10 seconds

_________________

How can i lose my faith in life's fairness when i know that the dreams of those who sleep on the feathers are not more beautiful than the dreams of those who sleep on the ground? - Jubran Khaleel Jubran

Intern
Joined: 16 Jul 2011
Posts: 16
Followers: 0

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

Re: DS - greatest common factor and least common multiple [#permalink]  01 Aug 2011, 10:04
Always; if we multiply two positive integers then the multiplication is same as the multiplication of their lcm and gcf. In this case lcm = 180 and gcf = 10 hence xy = (lcm)(gcf) = 180.10 = 1800
_________________
Manager
Status: Trying to survive
Joined: 29 Jun 2011
Posts: 190
GMAt Status: Quant section
Concentration: Finance, Real Estate
Schools: WBS (D)
GMAT Date: 12-30-2011
GPA: 3.2
Followers: 9

Kudos [?]: 79 [0], given: 94

Re: DS - greatest common factor and least common multiple [#permalink]  02 Aug 2011, 10:44
manishgeorge wrote:
Could some body help me to understand this a little better.

here is where I am getting stuck

GCF = 10, There for X = 10A nd Y = 10B where A and B are separate constants

for example 20 and 30, here the GDF is 10 and a = 2 and b = 3

sice we dont have a and b from this equation. this is insufficient

statement 2:

LCM is 180
so X*N1 = 180 and Y * N2 = 180

since we do not know the values of N1 and N2 this statement is not sufficient.

even if we combine, we dont have information to solve.

I see come body explaining the answer are LCM*GCD. Could you please tell me how you arrived at that equation

it's a general rule and can always applied .
if u want the details about how we arrived at that equation just let me know
_________________

How can i lose my faith in life's fairness when i know that the dreams of those who sleep on the feathers are not more beautiful than the dreams of those who sleep on the ground? - Jubran Khaleel Jubran

Re: DS - greatest common factor and least common multiple   [#permalink] 02 Aug 2011, 10:44
Similar topics Replies Last post
Similar
Topics:
If x and y are positive integers, what is the value of xy? 2 21 Dec 2005, 06:50
If x and y are positive integers, what is the value of xy? 6 22 May 2006, 07:19
If X and Y are positive integers, what is the value of XY ? 2 04 Sep 2006, 10:07
2 If x and y are positive integers, what is the value of xy? 10 22 Jun 2008, 12:05
6 If x and y are positive integers, what is the value of xy? 9 14 Jun 2010, 17:50
Display posts from previous: Sort by