Nine men and two boys are trekking through the jungle and they need to cross a river. They have a small inflatable boat and it's easy enough to row it across the river. The boat however can hold no more than one man or the two boys. How can they all get across? (HINT: Suppose there was only one man and two boys)
Explains the logical explanation to how 11 people can cross the river when the boat can only hold two boys at once.