Not a single person at my 2,000 student high school was born on December 16th

With a sample of 2000 students, the odds of no birthdays being on a specific day is about 1 in 240. The odds of there being at least one day in a given month with no birthdays is about 1 in 9. The odds of there being at least one day in the entire year with no birthdays is nearly 4 in 5.

Parents too drunk on St. Patrick’s day to get itup.

Well for each specific day on the calendar (let’s ignore leap years for simplicity) the probability that none of 2000 people were born on that day is (364/365)^2000 = 0.00414 or 0.41%.

But then what is the probability that *such a day exists at all on the calendar*? Unfortunately my long-lost stats skills escape me (and do not try asking a LLM, it will really confuse the concepts and give a rather wrong answer). Would be interested in seeing a proper solution but it’s probably quite decently likely that at least one day is birthday-less.

that’s my mum’s birthday

This is indeed mildly interesting! 👍🏼

If I did my math right*, there’s about a ~~21.8%~~ 78.2% chance that any given 2,000 student school would have one date of the year without any birthdays. So, this is ~~fairly~~ very common.

Probability that a specific date has no birthdays: Ps = ((3*364+365)/(3*365+366))^2000 = ~0.41%

Probability that any date in the calendar has no birthdays: Pg = ~~(1-Ps)^365.25~~ 1-((1-Ps)^365.25) = ~78.2%

*Although I factored in the existence of leap days in my calculation, I didn’t actually take into account that it is 1/4 as common on the calendar, which throws the calculation off a bit. I am not quite interested enough to go the extra steps, but most calendar dates will only deviate slightly from my estimates and February 29th is quite a bit more likely to have no birthdays.

Edit: I inverted my fraction and it’s actually about 4/5, not 1/5. Super common.

December 16th doesn’t exist. You heard it here first!

no one bangs on the ides of march?

[deleted]

It’s the day that shall not be named

Well nine months before December 16th is St. Patrick’s day, when people are generally too drunk to fuck.

The Birthdy Paradox would like to have a word .

Sending my dad this on his birthday (12/16)

That was my due date. I was born two days earlier.