Did You Know.......

[ToraToraTora]

in a room of 23 people there is a 50% chance that 2 of them share the same birthday (month and day)?

[jno]

some twins don't even share a birthplace

https://www.bbc.co.uk/newsround/35350306

carrot, if you had 32 days that would be a 100% chance of two of them being born on the same day. For a 50% chance you'd need fewer.

[nescio]

what you are calculating is the probability that each additional person has a different birthday from all those already present. Once this drops to less than 0.5, it means that it is more than 50% likely that two people do share the same birthday

[bhg481]

carrott - it's terminology. A probability of 0.5 is the same as a 50% chance. A probability of 1 is 100% chance, a probability of zero is 0% chance.

[carrot99]

Thank you again nescio and thank you jno.

[johnny.5]

in fact as soon as there were 367 people in the room there will be 100% chance that two will celebrate the anniversary of their birth on the same day

[bhg481]

Johnny - that's what I said at 11:06.

[nescio]

yes, because the probability that the 366th or 367th person does not share a birthday with anyone else is now 0/365 (or 0/366) - there are no possibilities left - so the overall product becomes zero.

[Canary42]

When I was a youngster at home, with 4 people in a room there was a 100% chance of 2 of them sharing the same birthday (hour, day, month,year).

[rowanwitch]

Oh heaven's canary, does that mean you have a twin.... Or was it two others.

[ZebuSanctuary]

// 100% chance of 2 of them sharing the same birthday (hour, day, month,year) //

And conversely, 0% chance (min, hour, day, month, year).