Quote:
Originally Posted by pdurrant
The sneaky bit of this question is that you don't need to identify which bag has the fake coins, just identify a bag with good coins.
Put two bags on the scale. Note how much they weigh (using up the penny).
Remove one of the bags (the scales still work, as they haven't gone back to zero yet). If the scale now shows exactly half what it did before, take the bag you've just removed from the scales.
Otherwise, take the bag you didn't put on the scales.
Crystal Maze?
|
That was a pretty good solution Pdurrant, and it wasn't even the one from the show.
The way they did it on the show was to take 1 coin from bag one, 2 coins from bag two, and 3 coins from bag three and weigh them all. If all the bags had real gold they would weigh 6 oz., but if bag 1 had the fake gold the coins would weigh 6.1 oz. If bag 2 had the fake gold the coins would weigh 6.2 oz., and if bag 3 had the real gold the coins would weigh 6.3 oz.
The show was an old rerun of Colombo and he was investigating a killing at a Mensa club, so very good coming up with a solution Pdurrant.