South Carolina High Energy Mathematics Teachers' Circle

Vladimir Arnold Mixes Tea and Wine

Vladimir Arnold

Suppose we have a barrel of wine and a cup of tea. A teaspoon of wine is taken from the barrel and poured into the cup. After stirring, a teaspoon of the mixture is taken from the cup and poured into the barrel. Now the barrel contains some tea and the cup contains some wine. Which volume is larger---that of the tea in the wine or of the wine in the tea?

From Problems for Kids from 5 to 15
V. Arnold 2004