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?

As there are 36 possible orderings (6 of red x 6 of black), limit would be ceil (log(36)/log(3)) = ceil(3.26185951)=4 but that might not be actually achievable.

Posted by Charlie on 2006-07-09 13:47:35