Weighing Medals

Almost a new year already, apparently I didn't do quite as much blogging this year, as I usually get about 40 posts a year and this year I only have about 30. I choose to blame it on my thesis rather than on my general laziness.

Anyway, I found a new puzzle over at Tanya Khovanovas Math Blog that I thought was sort of neat:

There is a collection of medals and one of them is known to be fake. There is 1 gold medal, 3 silver medals, and 5 bronze medals. A fake medal weighs slightly less than the corresponding real medal. All real medals of the same type weigh the same amount, but medals of differing types might not weigh the same amount. Using a balance scale and two weighings, find a strategy that is guaranteed to identify the fake medal.

Standard balance scale rules, of course. The balance scale can be envisioned as having two places to put stuff, and then you push a button and it will tell you either "left side heavy", "right side heavy", or "balanced". The button will only work two times and then the scale will break.

Its actually a pretty simple puzzle if you have done the other balance scale problems, it only took me a few minutes to get it, but I somehow was very satisfied with the answer.