Most people have difficulty understanding the birthday problem, because they can't wrap their brains around how the number of possible pairs increases exponentially as the number of people increases linearly. In a group of 75 people, there's a 99.9% chance that two will share a birthday.
The Odds Of Sharing A Birthday
Share the knowledge!
Key Facts In This Video
There are 23 people on the field during a football/soccer game: 11 per team, plus one referee. 00:23
For a group of 23 people, the probability that no two people share a birthday is 49.3%; the probability that two people do is 50.7%. 02:40
A group of 23 people equates to 253 possible pairs of people. 03:30