Twenty metal blocks are of the same size and external appearance; some are aluminum, and the rest are duraluminum, which is heavier.

Using a pan balance to determine how many blocks are aluminum, what is the minimum number of weighings to be done?

(In reply to re(2): Thoughts, spoiler? by Erik O.)

Ok, I just wanted to make sure I wasn't missing an "obvious" step. 

Posted by ajosin on 2005-06-06 18:45:40