The Birthday Problem in Probability: P(A) = 1 – P(not A)

The birthday problem is fun and surprisingly challenging: How many people need to be in a room before the probability that two people share the same birthday is at least 50%? To solve this problem, we find that it is much easier to compute 1 minus the probability that two people *don’t* share a birthday. This idea will be very useful in other problems.

This video was produced at the University of Washington, and we acknowledge funding support from the Boeing Company

%%% CHAPTERS %%%
00:00 Intro
02:29 Brute Force Comparisons
04:44 Brute Force Complications
06:18 The Easy Way
07:58 Why the Complement
10:01 Calculating the Complement
14:23 Homework: Computing the Complement
15:58 Warning: Factorials are Big
18:08 Outro