Among 100 coins exactly 4 are fake. All genuine coins weigh the same; all fake coins, too. A fake coin is lighter than a genuine coin.

How would we find at least one genuine coin using two weighings on a balance scale?

Source: 2010 Euler math Olympiad in Russia- authored by A.Shapovalov

(In reply to re(2): question for Kenny by Charlie)

Obviously my solution is still incorrect/incomplete.  Thanks to those who have pointed it out....

Posted by Kenny M on 2013-10-19 09:27:19