A bag contains 20 blue balls and 14 red balls. You remove 2 at a time.
If they are the same color, you add a blue ball to the bag.
If they are different colors, you add a red ball to the bag.
(Assume you have a supply of extra blue and red balls.)
Note: Each step replaces two balls with one ball, so the number of balls
eventually reaches one.
What will be the color of the last ball in the bag?
If you start with 20 blue balls and 13 red balls, what will be the color
of the last ball?
(Puzzle contributed by Sarah Hartman, CISC106 student, Sept 2013)