Puzzle

Started by Hobby, Yesterday at 05:37 PM

Previous topic - Next topic

0 Members and 2 Guests are viewing this topic.

Print
Go Down Pages1
User actions

Hobby

Yesterday at 05:37 PM
If you like puzzles here is one that you have to have a very high IQ to solve or a lot of time.  I solved it took me like 3 months.  I showed the puzzle to a lot of coworkers very smart people who gave up.


Here is the puzzle.

There are 12 coins identical in size and shape.  The difference is weight.  One coin is slightly lighter or heavier than the other 11. Your job is by using a balance scale to identify the odd coin and lighter or heavier from that of the other 11.  You have only 3 attemps with the scale. There are no tricks this can be done everything in 3 weighing or less I promise. Many will place 6 coins on onesie and 6 on the other.  Wasted attemp.  The scale will tip but you won't know heavy or lighter and which is the coin.

So if you want to give it a try go for it.  I have the answer.. and no this is not a joke.  Use logic and you will figure it out!
Hobby

HighStepper

#1
Yesterday at 07:04 PM
I can solve this puzzle when only 9 coins are used, in two weighings. I'm thinking it would probably take the full three weighings allowed for 12 coins.

Too much sex is still not enough.

dogwalker

#2
Yesterday at 07:42 PM
I've solved it.  It took me about 15 minutes and was pretty easy for me.  I don't think that means I have a super high IQ. However I consider myself to be good with visualizing and analytical, math-type things.  Hobby gave me a very useful clue which was to use logic but I re-interpreted that as "I should think differently."

So I started with the extreme opposite of the usual approach to put 6 coins on each side since Hobby indicated thinking like that would get you nowhere. Actually there is a 50% chance the 6 coins on each side approach works but that is not a solution to the puzzle because for the other 50% of the time 4 weighing attempts would be needed.
Obviously putting single coins on each side would take too many attempts.
However as I worked my way up to increasing numbers of coins on each side of the scale I found there was an optimum division of coins that allowed me to solve the puzzle.
Once I knew how to do it, it was embarrassing to me how simple the solution is.
I could give another hint that might help others to solve it but perhaps what I said above is enough and perhaps I should let others try to solve it first before I give another hint.

Hobby

#3
Yesterday at 08:38 PM Last Edit: Yesterday at 08:41 PM by Hobby
It's a good puzzle and there is only one way that will always find the odd coin in no more than 3 weighs.

It took me 3 months working on now and then.  If you split into 6 and 6 tells you what you already know so it's a wasted move.  Another hint is if a group weighs the same equal that tells you useful information.
Hobby

bats

#4
Yesterday at 09:12 PM
I solved it using DeepSeek. Took a few seconds.

Hobby

#5
Today at 02:47 AM
I didn't know the answer could be googled and solved.  When I solved this puzzle it was like 1978...lol no internet no google... lol
Hobby

dogwalker

#6
Today at 09:57 AM
The strategy that allows the puzzle to be solved works whether the first weighing is balanced or not.
So I found there actually are 2 solutions to the puzzle in terms of the order of what can happen.
In one solution the coins are balanced in the first weighing,
In the other solution they are not.
However the odd coin can be identified in both cases using the same strategy.
Print
Go Up Pages1
User actions