I'm not sure if this can be said to be a trick question... but maybe.
Jack, John and Jill go up the hill with five pails to a place where three springs are. Each of the five pails has an 8 litre capacity. One of the springs gives 2 litres of water in one minute while each of the other two gives 1 litre of water in one minute. It is impossible to use one spring to fill two pails at the same time, and it takes less than 2 minutes but more than 1 minute to take a pail from one spring to another one. What is the shortest time Jack, John and Jill need to fill all five pails to their capacity?