DS Hardcore Numbers

[mmslf75]

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 ??

[pandeyvineet24]

Are you sure you got the question right ?. Question stem has 2*X*5*Y, so the product will always be even.

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 ??

[rohan_vus]

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...

[papgust]

Rohan, rightly said. Even i feel that it should be C.

[mehravikas]

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.

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]

Are you sure you got the question right ?. Question stem has 2*X*5*Y, so the product will always be even.

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]

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.

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...

Vikas,

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.

[mehravikas]

God how could I forget that

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.

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...

Vikas,

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.

[Testluv]

Hey, it happens to the best of us!