I work with a statistician who told me today that in any group of 30 people, there is like a 99.999% chance that two of them will have the same birthday (same date, not necessarily year). He explained the math of it, but I didn't really understand how it brought him to his conclusion. There are 34 people in our office, so he told me randomly eliminate 4 people and test it out. The second person I talked to had the same birthday as me!
Please post your birthday and we'll see if there are any duplicates in the first 30 respondants... Mine is April 3rd.
April 19th
July 21.
If I say April 19th are we done?
November 12th
Not sure about that theory. I have 70+ people in my office and we have a birthday list, nobody shares the same birthday
We do share common birthdays (earthly birth) with many others on this planet.
World Population - 6,333,599,551
Days in the Year - 365
January 17th
may 9th
September 4th
April 17th. Now if you had been born two days before, ASHTHECAT, the experiment would be over. LOL
April 29thNeville wrote:
June 24th.
Susan wrote:
> Not sure about that theory. I have 70+ people in my office and
> we have a birthday list, nobody shares the same birthday
>
Well, that's the thing about statistics...they make a prediction within some level of confidence. The prediction that 1 person in 30 will share a birthday is based on "I am sure of this to x.x%," and x can NEVER be 100%. Obviously, your office lies outside the confidence interval of the prediction. That does not invalidate his analysis nor his prediction (but he SHOULD state his confidence interval to clarify the reliability of his prediction).
15 October
Another 2 day miss. Mine's October 13
I've met two people with the same birthday (one was even the same year...we were born only hours apart in different towns) as me and a BUNCH within one or two days....as common as it must be statistically, I still find it fascinating.
April 25th, same as Al Pacino. My cousin has the same birthday as I, only one year later. My sister's birthday is the same as another cousin's. A really bad birthday-based b-movie is Happy Birthday to Me.
me, may 23, I also play basketball with the a guy with the exact same birthday as well, but i think i am like 12 hours older than him, still i think it's pretty cool though.
i also know someone on 12 november neon, does that mean i win a prize?
:-P
August 26
July 12th... hmmmm... so much for that statistic. ; )
October 26. Same day as Hilary Clinton, Pat Sajak, Leon Trotsky, and Jackie "Uncle Fester" Coogan.
April 11.
The 99.9% chance seems to makes sense based on the following:
Say you had only 4 people, numbered 1, 2, 3, and 4. You would have the following combinations:
1 could have the same birthday as 2
1 could have the same birthday as 3
1 could have the same birthday as 4
2 could have the same birthday as 3
2 could have the same birthday as 4
3 could have the same birthday as 4
This gives 6 possible matches with only 4 people. Below, I have laid it out more visually:
(1,2) (1,3) (1,4)
(2,3) (2,4)
(3,4)
The top row has 1 fewer combination than the number of people involved (4 people involved minus 1 = 3 combinations in the top row). Each row below it decreases by 1 combination (top row has 3, middle row has 2, bottom row has 1).
If you extend this out to a population of 30 people, you will get the following:
29 + 28 + 27 + 26 + 25 . . . .all the way down to 1. If you add this up it comes to 435 possible matches for a group of 30 people.
I have no idea what the statistical formula would be to figure all this out (and I'm too lazy to look it up in my statistics book, which is about 10 feet away), but it seems like there are a lot of possible matches among 30 people.
7 July
fwiw - march 10
There sure are quite alot of april b-days. i bet nobody shares mine, i've never met anyone with my birthday. And in my job i see the birthdates of every person i set up for insurance and haven't seen anyone with my birthday.
I share birthday with Osama Bin Laden, James Earl Ray and Chuck Norris.
woo hoo
I met someone at my job who has the same birthday as me - and it was while someone was discussing this statistical odditity - perhaps someone is tapping badmovies.org? the horror!
August 10
Solution to the Birthday Problem (http://images.beggerlybend.com/puzzles/birthdays.html)
Looks like The Burgomaster was on the right track, even if the original statistician wasn't completely correct with his 99.99% prediction. At 30 people it's about a 70.63% chance. If you have a good calculator that page will show you how to do all the calculations yourself.
So, it would seem that to be absolutely sure you get two people who share the same birthday the actual number would have to be 367. Right?
Any doubles yet? Anybody keeping track?
July 31.
The prof ran this experiment in a math class I had once...only took ten tries to find a match.
My father and my father-in-law were both born on March 18.
January 12th.
My brother's birthday is June 23.
October 15, 1982
Brother R
ulthar and Brother R are both October 15.
Do they win a prize?