If you have 12 golf balls and one weighs a little more or a little
less than the other 11, can you figure out which one it is by weighing
the balls only three times?  How?

Yuppp here a normal weighing machine won't work out.Take simple rod
find out it's exact centre by balancing.
Tie six balls each on either side of rode.
step I->Make the first wiegh by trying to balance rod with six balls
each on either end
Result->one of the side will be found lighter.
Next get hold of all golf balls on the side which wighed less in first
try and ###Repeat the above procedure with three ball set on either
side.
->Again one of the side will be lighter.Get hold of lighter side balls

Put one ball each side.if they wigh equally  then the one which wasn't
used is the odd one .
else u know which one was the culprit

regards

Rommel,
It's more complicated than that, but I agree that one needs a balance scales.
The question states that the one ball could be lighter OR heavier, but
we don't know which.
I have read this problem a couple of times.  I think you have to
exchange balls, but that may not be so.
I thought Pinkfreud would be able to do this and also give us a site
with the solution, but I expect that she has more important things to
do right now.
Cheers, Myoarin

This is a restatement of an old problem. Usually the objects are coins
rather than golf balls, but that doesn't matter in arriving at a
solution. This article (and the other articles linked at the bottom of
the page) may be of interest:

http://www.cut-the-knot.org/blue/OddballProblem2.shtml

Hi, Pink (should you come back),
You didn't let us down!  I suspect that Researchers get a nudge when
their name is mentioned, but maybe not.  Hope the cookies didn't burn.
Merry Christmas to you (and others of the faith), and thanks for so
much interesting and entertaining information.
Regards, Myoarin