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Question of the Day - 26th August, 2009

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Question of the Day - 26th August, 2009

by quant-master » Tue Aug 25, 2009 3:59 pm
Question 1:

If x is an integer, is y an integer?
(1) The average (arithmetic mean) of x, y and y-2 is x.
(2) The average (arithmetic mean) of x and y is not an integer.

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by kbharadwaj.1987 » Tue Aug 25, 2009 4:48 pm
I think the answer has to be A.
stmnt 1:
avg of x,y,y-2 is x
=> x+2y-2=3x
=> 2y-2=2x
=> x=y-1
=> y=x+1
=> y is an integer as we know that x is an integer
sufficient
stmnt 2:
avg of x and y is not an integer:
=> x+y/2 is not an integer.
y could be anything from an integer to a non-integer
because let's say x=5 and y=6, then the average of these two would give 5.5, which is not an integer, and also if x=4 and y=6.2, we get a non-integer avg value.
Thus insufficient.
OA "A"
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by pradeepsarathy » Tue Aug 25, 2009 5:28 pm
IMO A-

explanation - same as kbharadwaj.1987's
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