The process seems chaotic: each extraction depends on chance and the balls come and go. However, the final answer is completely deterministic from the first moment.
The last ball
Riddle statement
In an urn there are white and black balls.
You repeatedly draw two balls:
- if they are the same color, you remove them and put a black one;
- if they are a different color, you remove them and put a white one.
When there is only one ball left, what will its color depend on?