You have six balls - three red and three black. All the red balls weigh differently, i.e. one of them is heavy, the other medium, and the third light. Each red ball has a black twin of the same weight. A heavy and a light ball put together weigh as much as two medium balls.

What is the least number of weighings required on a balancing scale to determine which is which?

(In reply to Less trivial boundary by Steve Herman)

I agree that you can sort the red and black balls in five weighings. 

But, as yet, I also have not concluded that five is the minimum.

Posted by Dej Mar on 2006-07-07 16:06:41