mmslf75 wrote:Is the product 2*X*5*Y an even integer ?
1) 2 + x + 5 + y is an even integer
2) x - y is an odd integer
Answer :: C
Source :: GMATCL
IMO B
Any clue why B is rejected ??
DS Hardcore Numbers
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
pandeyvineet24
- Legendary Member
- Posts: 527
- Joined: Mon Jun 02, 2008 9:14 am
- Location: Atlanta
- Thanked: 17 times
Are you sure you got the question right ?. Question stem has 2*X*5*Y, so the product will always be even.
-
rohan_vus
- Master | Next Rank: 500 Posts
- Posts: 189
- Joined: Thu Apr 03, 2008 2:03 pm
- Location: USA
- Thanked: 21 times
Not sure abt the question
But if the question is what it is , then i see X and Y are not mentioned as integers..and answer must be C then
In that case B cant be the answer coz consider X = 1.5 and Y = .5 ( considering any number coz its not mentioned they are integer) then X - Y = 1. which is an odd integer but your expression 2*X*5*Y is not an even integer
But 2*X*5*Y will surely be an an even integer if we can prove X*Y is an integer..
If you take A alone then we see x + Y is an odd integer if X is 1.3 and y is 1.7...so A alone not sufficient
Combining both A and B you can see X - Y = odd integer and X + Y = odd integer then X and Y are definitely integers...But y so , simple reason , use stmnts from A and B ==> ( X + Y) + ( X - Y) = odd + odd = even ==> 2X = even then X got to be an integer ...it X is an integer then Y has to be an integer...
But if the question is what it is , then i see X and Y are not mentioned as integers..and answer must be C then
In that case B cant be the answer coz consider X = 1.5 and Y = .5 ( considering any number coz its not mentioned they are integer) then X - Y = 1. which is an odd integer but your expression 2*X*5*Y is not an even integer
But 2*X*5*Y will surely be an an even integer if we can prove X*Y is an integer..
If you take A alone then we see x + Y is an odd integer if X is 1.3 and y is 1.7...so A alone not sufficient
Combining both A and B you can see X - Y = odd integer and X + Y = odd integer then X and Y are definitely integers...But y so , simple reason , use stmnts from A and B ==> ( X + Y) + ( X - Y) = odd + odd = even ==> 2X = even then X got to be an integer ...it X is an integer then Y has to be an integer...
-
mehravikas
- Legendary Member
- Posts: 1161
- Joined: Mon May 12, 2008 2:52 am
- Location: Sydney
- Thanked: 23 times
- Followed by:1 members
Why not 'E'?
X = 0, Y = 1or X = 1, Y = 0 would still given the desired result but depending on X and Y the product could be even or odd.
X = 0, Y = 1or X = 1, Y = 0 would still given the desired result but depending on X and Y the product could be even or odd.
rohan_vus wrote:Not sure abt the question
But if the question is what it is , then i see X and Y are not mentioned as integers..and answer must be C then
In that case B cant be the answer coz consider X = 1.5 and Y = .5 ( considering any number coz its not mentioned they are integer) then X - Y = 1. which is an odd integer but your expression 2*X*5*Y is not an even integer
But 2*X*5*Y will surely be an an even integer if we can prove X*Y is an integer..
If you take A alone then we see x + Y is an odd integer if X is 1.3 and y is 1.7...so A alone not sufficient
Combining both A and B you can see X - Y = odd integer and X + Y = odd integer then X and Y are definitely integers...But y so , simple reason , use stmnts from A and B ==> ( X + Y) + ( X - Y) = odd + odd = even ==> 2X = even then X got to be an integer ...it X is an integer then Y has to be an integer...
-
mmslf75
- Legendary Member
- Posts: 503
- Joined: Sun Aug 09, 2009 9:53 pm
- Thanked: 31 times
- Followed by:2 members
pandeyvineet24 wrote:Are you sure you got the question right ?. Question stem has 2*X*5*Y, so the product will always be even.
mmslf75 wrote:Is the product 2*X*5*Y an even integer ?
1) 2 + x + 5 + y is an even integer
2) x - y is an odd integer
Answer :: C
Source :: GMATCL
IMO B
Any clue why B is rejected ??
The question is right, but not traditional. That's why I have posted here ...
-
Testluv
- GMAT Instructor
- Posts: 1302
- Joined: Mon Oct 19, 2009 2:13 pm
- Location: Toronto
- Thanked: 539 times
- Followed by:164 members
- GMAT Score:800
Vikas,mehravikas wrote:Why not 'E'?
X = 0, Y = 1or X = 1, Y = 0 would still given the desired result but depending on X and Y the product could be even or odd.
rohan_vus wrote:Not sure abt the question
But if the question is what it is , then i see X and Y are not mentioned as integers..and answer must be C then
In that case B cant be the answer coz consider X = 1.5 and Y = .5 ( considering any number coz its not mentioned they are integer) then X - Y = 1. which is an odd integer but your expression 2*X*5*Y is not an even integer
But 2*X*5*Y will surely be an an even integer if we can prove X*Y is an integer..
If you take A alone then we see x + Y is an odd integer if X is 1.3 and y is 1.7...so A alone not sufficient
Combining both A and B you can see X - Y = odd integer and X + Y = odd integer then X and Y are definitely integers...But y so , simple reason , use stmnts from A and B ==> ( X + Y) + ( X - Y) = odd + odd = even ==> 2X = even then X got to be an integer ...it X is an integer then Y has to be an integer...
if either of x or y were zero, then the product of the expression in the question stem would be zero, and zero is an even integer.
Kaplan Teacher in Toronto
-
mehravikas
- Legendary Member
- Posts: 1161
- Joined: Mon May 12, 2008 2:52 am
- Location: Sydney
- Thanked: 23 times
- Followed by:1 members
God how could I forget that 
Testluv wrote:Vikas,mehravikas wrote:Why not 'E'?
X = 0, Y = 1or X = 1, Y = 0 would still given the desired result but depending on X and Y the product could be even or odd.
rohan_vus wrote:Not sure abt the question
But if the question is what it is , then i see X and Y are not mentioned as integers..and answer must be C then
In that case B cant be the answer coz consider X = 1.5 and Y = .5 ( considering any number coz its not mentioned they are integer) then X - Y = 1. which is an odd integer but your expression 2*X*5*Y is not an even integer
But 2*X*5*Y will surely be an an even integer if we can prove X*Y is an integer..
If you take A alone then we see x + Y is an odd integer if X is 1.3 and y is 1.7...so A alone not sufficient
Combining both A and B you can see X - Y = odd integer and X + Y = odd integer then X and Y are definitely integers...But y so , simple reason , use stmnts from A and B ==> ( X + Y) + ( X - Y) = odd + odd = even ==> 2X = even then X got to be an integer ...it X is an integer then Y has to be an integer...
if either of x or y were zero, then the product of the expression in the question stem would be zero, and zero is an even integer.
