this post was submitted on 02 May 2024
690 points (96.0% liked)
Showerthoughts
29819 readers
1089 users here now
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. A showerthought should offer a unique perspective on an ordinary part of life.
Rules
- All posts must be showerthoughts
- The entire showerthought must be in the title
- Avoid politics
- 3.1) NEW RULE as of 5 Nov 2024, trying it out
- 3.2) Political posts often end up being circle jerks (not offering unique perspective) or enflaming (too much work for mods).
- 3.3) Try c/politicaldiscussion, volunteer as a mod here, or start your own community.
- Posts must be original/unique
- Adhere to Lemmy's Code of Conduct
founded 1 year ago
MODERATORS
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
The probability of 2 people having the same birthday is 1 in 365 because it's the same as picking person A's birthday as a specific day in the year and checking whether person B has their birthday on that date.
Now, the reason the number is so low is that you are basically comparing pairs and with 23 people there are 253 different pairings (23 choose 2 or
22*23/2). With each pair having a 1/365 chance to have the same birthday and having 253 distinct pairs, you would have to fail a 1/365 check 253 times in a row. The formula you can use for the success rate is1 - (1-p)^xwith p being the probability and x the number of trials, so in this case1 - (1 - 1/365)^253 = 0.5004In essence, the unintuitive part of the "paradox" is how fast the number of possible pairs grows the more people you add.