spriya wrote:

arjtryarjtry wrote:

Is product 2*x*5*y an even integer?

a.) 2 + x + 5 + y is an even integer

b.) x - y is an odd integer

pls give explanation...

IMO D

Any number multiplied by 2 is even

hence irrespective of choices we can determine the answer

OOPS silly mistake

i left out possibility of fractions

just occurred to me after seeing the posts

I would re analyse this problem :

consider (1) 2+x+y+5=n n is a even integer => x+y=n-7 => x,y can be fractions or integer => insufficient

consider (2) x-y=m m is odd integer

but here also x,y can be either integer or fraction => insufficient

now consider both (1) and (2) => 2x=m+n-7=> x=(m-7+n)/2 m-7 is even and n is even hence x is integer

also 2y= n-7-m => y=(n-7-m)/2 => m+7 is even n is even hence y is integer

=> 2*x*y*5 is even integer

hence (C) is IMO.

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