I’m doing something that I should have done a long time ago: collecting a series of posts into one single post. The following links comprised my series on what I’m calling the Facebook birthday problem, a simple variant of the classic birthday problem in probability.
Part 1: Statement of the Facebook birthday problem.
Part 2: Solution for expected value.
Part 3: Finding the variance (a).
Part 4: Finding the variance (b).
Part 5: Finding the variance (c).