On a recent holiday to the seaside the Quiz Master Shop team was enjoying a restorative pint overlooking the harbour. We noticed that the biggest boat had a ladder that was hanging over the side and into the water, with four rungs submerged. In fact the top of the fourth rung was exactly on the surface of the water.
Each of the rungs was a cylinder with a diameter of two inches, and the gap between the rungs was eleven inches. The tide was rising at a rate of 18 inches per hour.
So how many rungs were submerged two hours later when we left the harbourside pub?
There is no maths required for this. The boat (and the ladder) will rise with the tide, leaving the same number of rungs submerged.