Posts from — November 2009

Here’s a puzzle a co-worker shared with me recently. See how you do with it!

Suppose you have five bags of gold coins. All of the coins weigh exactly 1 lb each except for all of the coins in one bag whose coins weigh 1 lb 1 oz each. The bags are unmarked, and there is no visible indication as to which bag holds which coins. The bags may contain different quantities of coins.

Suppose you have a scale on which you can make exactly one instantaneous measurement – put something on the scale, push the “Weigh” button, and you get a reading of the weight at the moment the button is pushed.

Using the scale, is it possible to identify which of the 5 bags contains the heavier coins with only a single measurement? If so, how?

Show Answer ▼

(I haven’t forgotten about you … I’ve just been really, really, really busy in a way that seems to be soaking up an awful lot of my personal time. Real Soon Now, I will be increasing my posting frequency here back to the levels I know you’ve all come to expect.)

There was a wonderful story about geocaching in the Sun-Sentinel this weekend, featuring a mention of Yours Truly. Check it out.