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: Thoughts, spoiler? by ajosin)

I miscounted.

I tend to do that when I'm in a hurry.

Posted by Erik O. on 2005-06-06 15:42:26