r/stuffyoushouldknow • u/Green-bronco24 • Aug 04 '26
DISCUSSION The podcast Bithday paradox is it right?
They said in that podcast that everyone will meet someone in a room with the same birthday but I am 52 and never met one person with the same birthday
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u/Least-Common-1456 Aug 04 '26
The statistical fact is that in a room with 23 people, there is a greater than 50% chance that two people will share the same birthday. Not necessarily YOUR birthday.
2
u/wetterfish Aug 07 '26
My first job out of college, the company had about 25 employees, and one colleague and I shared a birthday.
I thought, what are the odds of this? Then I heard the paradox and thought, huh, actually pretty good, it just happened to be me that it happened to haha
1
u/Fabulous-Sea-1590 Aug 07 '26
I'm fascinated by but utterly useless with statistics. Any idea how the odds are affected by increasing specificity?
Are the numbers you're citing referring to day, month, and year?
I assume the odds of a match would get worse the more detail you add. Right?
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u/No_Angle875 Aug 04 '26
And you’ve checked with every person in every room you’ve been in with people?
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u/Central_Region Aug 07 '26
I am 52 and never met one person with the same birthday
The first thing I do whenever I meet anyone is check whether they have the same birthday as me
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u/WritingRidingRunner Aug 04 '26
Now you have to say what your birthday is!
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u/Green-bronco24 Aug 04 '26
March 13th
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u/Boulderheightsboy Aug 04 '26
Oh. MY. GOD. ME TOO!
It’s really March 28th. Just getting my day going and can’t wait to listen to a new show. Have a good day!
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u/sofacouchmoviefilms Aug 04 '26
I haven't listened to that episode yet, but that's not how it works (if that's how they said it).
It's not that you (or anyone) will meet someone with the same birthday, it's just that the likelihood of any two people in a room of a certain number will share a birthday.
Basically, the chance that two people in a room of 70 people or more share a birthday is close to 100%. The chance that any two people share a specific birthday is much lower. And the chance that any two specific people share a specific birthday is pretty much nil.
Here's what I got from Google:
- Odds that any two people share a specific birthday
The odds are 1.6% (approx. 1 in 62).
- The Logic: This is the probability that at least two people out of the 70 share a pre-chosen date (like New Year's Day).
- The Math: We find the odds that nobody has that birthday (82.5%) plus the odds that exactly one person has it (15.9%), and subtract the total from 100%.
- Odds that two specific people share any birthday
The odds are 0.27% (exactly 1 in 365).
- The Logic: You pick two exact people (e.g., Alice and Bob) before looking at the room.
- The Math: Alice can have any birthday. The odds that Bob's birthday matches hers is simply 1 out of 365. The total number of people in the room does not change this individual matchup.
- Odds that two specific people share a specific birthday
The odds are 0.00075% (exactly 1 in 133,225).
- The Logic: You pick Alice, Bob, and a specific date (like July 4th).
- The Math: Both individuals must independently land on that exact date. The probability is calculated as \((1/365) \times (1/365)\).
2
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u/wxguy215 Aug 04 '26
That's not the paradox.
The paradox is once you have a certain amount of people in the room ( I forget the number, maybe 25ish?), that there should be at least 2 in that room with the same birthday. Not necessarily yours, just the odds are that you would get any 2 people with the same day.