The Birthday Paradox

Abstract

This paper teaches and expands on the basics of probability using the birthday paradox. This was chosen as it is an interesting topic with surprising results, which should encourage beginners to read on. The paper shows that if there are 23 people in a room, then there is a 0.5 probability that people in the room share the same birthday. A general formula is then given which can be applied for different desired probabilities, numbers of items and numbers of possible outcomes.