Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

There is an urn of N balls, each of a unique color. In each step one takes out 2 balls without replacement, changes the color on the 2nd ball to that of the first ball and returns them back to the urn. What is the expected number of steps until all the balls in the urn are of the same color?

share|cite|improve this question

As @ShaiCovo mentions in a comment above, this question is a duplicate of and has been answered there.

share|cite|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.