1. The classic "Three Jugs" problem: Two friends who have an eight-quart jug of water wish to share it evenly. They also have two empty jars, one holding five quarts, the other three. How can they each measure exactly 4 quarts of water?

Source: Cut-the-knot, who attributes the puzzle to Siméon Denis Poisson.

2. 3 people carry 5 pails (each with capacity 8L) to a place where there are 3 springs.  One of the springs gives 2L/minute and the other two give 1L/minute.  It is not possible to use one spring to fill two pails simultaneously.  It takes less than 2 minutes and more than 1 minute to take a pail from one spring to another.  What is the shortest time it takes for them to fill all five pails?  How?

Source: unknown