Help with a Brain Teaser...

[JACKHAMMER]

You are given 12 pennies and a balance. One of the pennies is fake and may be either heavier or lighter than a real penny. You can only use the balance 3 times, how can you for sure tell which penny is the fraud?

 

[PrincessGuard]

Easy. Split pile into 2. (* is fake)

6* --- 6
3* --- 3
1* --- 1 or 1 --- 1

Edit: Whoops. Didn't notice that it could be lighter or heavier. Disregard 🙂

 

[floccus]

Its too late to think now, but I've solved this b4... its not that hard when you get into it.

 

[JACKHAMMER]

Originally posted by: floccus
Its too late to think now, but I've solved this b4... its not that hard when you get into it.

It's never to late to think! 🙂

 

[zsouthboy]

Well it would be easy if the fake one was only heavier or only lighter.... gimme a minute to think..

 

[crypticlogin]

Google for "Twelve Coins Problem". This problem is as old as dirt and been rehashed for longer. 😉

 

[JACKHAMMER]

Thanks, don't know why i didn't think of that..

 

[deftron]

nm