A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

When the boat is floating on the water, it contains all the apples. Therefore, the apples have already displaced the water equal to their own volume. Now, it does not matter if they eat two or four dozen of apples, the water level will remain the same.