> > It ain't that complicated.

Oh, yes it is!


> > Put 6 on one side and 6 on the other.
> > Put aside the light six and put 3 on one and 3 on
the other. Put aside the light 3 and put one on one
side and one on the other. If they are the same mass,
the one in you hand is heavier. If they are different it's
the one on the lower pan.

Ahh, but you forget one crucial point!

You don't know if the marble you're after is heavier OR
lighter than the others. Do it your way, and you'll have
to weigh 4 times, not 3, as in gabby's excellent and
correct solution.

I trust someone (that would have to be Sam, i
suppose?) will add this excellent puzzle to the Brain
Food menu?

Trav"likes puzzles which you have to work hard with
paper and pencil to work out"holt.