# Plep's Puzzles

Name:

## Monday, December 18, 2006

### Water Puzzle

There are three glasses on the table - 3, 5, and 8 oz. The first two are empty, the last contains 8 oz of water. By pouring water from one glass to another make at least one of them contain exactly 4 oz of water.

steven said...

Here's one way of doing it :-

- Fill the 5oz glass from the 8oz (0 - 5 - 3).
- Fill the 3oz glass from the 5oz (3 - 2 - 3).
- Pour the contents of the full 3oz glass into the 8oz (0 - 2 - 6).
- Pour the contents of the 5oz glass (i.e. 2oz) into the 3oz. (2 - 0 - 6).
- Fill the 5oz glass from the 8oz (which contains 6 oz). (2 - 5 - 1).
- Fill the 3oz glass from the full 5oz glass. As the 3oz glass already contains 2oz, this will mean that 4oz are left in the 5oz glass. (3 - 4 - 1).

There is another possible solution here - http://www.cut-the-knot.org/water2.shtml .

Probably the easiest way to solve a puzzle like this is by drawing a 'graph' mapping out all the possible routes - there's an example at http://www.cut-the-knot.org/wgraph.shtml .

January 1, 2007 at 5:28 AM