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(3): between... by Charlie)

That's strange, because I said in the queue that it would take more than 10 weighings, and pcbouhid agreed.  If the interpretation pcbouhid expected was to count the number of duraluminum blocks rather than which was which, I think a solution under 10 weighings would be well possible.

Posted by Tristan on 2005-06-06 23:54:38