Eating soup

Eating soup

Alberto and Benito are two brothers who are having soup to eat. Three liters of soup are distributed in separate dishes and in equal parts. Alberto drinks his soup twice as fast as Benito. But when Benito observes that Alberto has finished the soup of the dish, he gives half of his. In this way they continue to eat until Alberto finishes the soup of his plate and Benito gives him half again.

The situation is repeated until the two have finished with all the soup.

How much soup has each one taken?


Since the two drink soup during the same time and it is known that Alberto consumes it twice as fast as Benito, we can deduce that Alberto takes two liters and Benito only one.

It is also possible to solve this problem by mathematical methods looking for the limit of the infinite succession of the soup distribution, thus the quantity S of soup left after N deals are: S = 3 / 4N.