TWELVE COINS
Here is a challenger. First one to solve it gets public recognition unless you eschew it.
You have twelve coins and an equal arm balance–nothing else. The twelve coins all look alike and seem to be identical in all respects. Eleven of the coins are identical in weight. The twelfth has a different weight than the other eleven, but you do not know whether it is lighter or heavier than the other eleven (you cannot tell the weight difference by feel or appearance).
This is not a trick question–just straight logic. There are two different solutions. (That should really annoy you after you have been struggling with this for several hours trying to find even one solution.)
Problem: Determine in just three weighings with the equal arm balance which one is the counterfeit coin and whether it is lighter or heavier than the other eleven, against any defense.
You may put any number of coins on either side and move them on and off the balance at will, but each time you change the location of any coin counts as a separate weighing. (Suggestion: Number the coins at the outset, so you and I can keep track of the coins in your solution.)
Send your solution to info@johnlowepc.com. First time/dated e-mail wins.
Challenger puzzle – 12 coins
TWELVE COINS
Here is a challenger. First one to solve it gets public recognition unless you eschew it.
You have twelve coins and an equal arm balance–nothing else. The twelve coins all look alike and seem to be identical in all respects. Eleven of the coins are identical in weight. The twelfth has a different weight than the other eleven, but you do not know whether it is lighter or heavier than the other eleven (you cannot tell the weight difference by feel or appearance).
This is not a trick question–just straight logic. There are two different solutions. (That should really annoy you after you have been struggling with this for several hours trying to find even one solution.)
Problem: Determine in just three weighings with the equal arm balance which one is the counterfeit coin and whether it is lighter or heavier than the other eleven, against any defense.
You may put any number of coins on either side and move them on and off the balance at will, but each time you change the location of any coin counts as a separate weighing. (Suggestion: Number the coins at the outset, so you and I can keep track of the coins in your solution.)
Send your solution to info@johnlowepc.com. First time/dated e-mail wins.