What day is your birthday?
- Thread starter dukedevilz
- Start date
This group has beaten the typical odds. 30 birthdays with no matches. Only a 30.3% chance of that happening. But, you'll also notice how close several of the birthdays are. Ones on Aug 28, 29th, and 30th. Ones on Sep 20th & 21st. Ones on November 5th & 6th. And finally, birthdays on December 17th and 18th.
This is often referred to as the birthday paradox. It's not intuitive. Most people are looking at the odds of sharing their birthday with the other 22 people. The odds of any two random people sharing their birthday is 1/365 (not counting for leap year). Extremely low. However, you need to look at all of the permutations, not simply comparing your bday with everyone else. 23 people gives you 253 possible combinations. You calculate it by figuring you have 22 possible matches, the next person has 21 because your birthday has already been factored in, the next person has 20 possible matches... all the way down to the final two people (22+21+20+19... +1). Another way to compute this is n * (n-1) / 2. So, it would be 23 (22) / 2 = 253).
The odds of two people not having the same birthday is 99.726027% (364/365)
-If you have 23 people, you have 253 working combinations. Meaning, you need to multiple .99726027 by itself 253 times. So...
.99726027 ^ 253 = 0.49952234 (the odds of not having a birthday match)
1 - .49952234 = .50047777 (odds of having a birthday match)
Technically, 50.048% of finding a birthday match with 23 people. You would be right roughly 50% of the time.
-With 30 people, there are 435 birthday combinations (30 * 29)/ 2 )
.99726027 ^ 435 = .30318317
1- .30318317 = .69681683
69.68% of having a birthday match with 30 people.
If we get to 40 people, the odds will increase to 88.2%. So yes, get 10 more people, and the odds are going way, way, up.
^Of course, we also have to consider that 435 of the combinations have already not worked. But, the next 10 birthdays would yield an additional 345 possibilities.
just like the lottery
someone will beat the odds
you could take 23 people and have them pick a number between 1-12, then have the matches pick a number between 1-31 but that is just folding numbers
take March 31st for instance, you could give it a number of 31 or the true number it has is 90
do you think if you made 10 bets on the 23 that you would win half of them?
i would take that bet every time
It surprised me when I first heard about it. But, the stats don't lie. This video probably explains it better than I could.
If you took that bet every time, the results would be negligible, assuming the sample size was large enough - and the amounts were the same. You would win just as much as you lose.
Ditto. What do I win?
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I’ve heard of it before. Seemed pretty crazy the first time.
30 November, me Coach Joe B. Hall (UK in case you forgot), Dick Clark, Mark Twain, Winston Churchhill and the Battle of Franklin (TN in the civil war)
EvilMonkeyInTheCloset
Well-Known Member
I’ve got Bill Murray, Stephen King, Leonard Cohen, Jerry Bruckheimer, Ethan Coen, Faith Hill, and, most importantly, Ricki Lake.
Nice! May 15th it is. I've actually had two different roommates with this same birthday. Must be something about August!
If I'm counting right, I'm showing 36 responses. We found a match on the 32nd response. 50% chance you get two separate birthday matches with 45 responses.
I don’t think I’ve ever actually met anyone that has my birthday, at least not that I can remember.
We win!!!!
IUFanBorden, isn't it nice to have the absolute best birthday anyone can have? That's not hyperbole. Of all the days of the year, there isn't a single day that is a better day to be your birthday than july 3.
Here is the evidence:
-The next day is always a holiday so you always have the day after your birthday off.
-There are always festivals and parties and things to do on July 3.
-Its in the heart of the summer so good weather
-it's 6 months from Christmas so you don't get screwed on presents
You never have to look in the calendar to see what day your bday falls on cause it doesn't matter, it's always on a holiday!
**** that guy IUBorden, you don't need him you got me! And Tom Cruise, Frank Tanana and Theemu Selanne.
We had another match, a few posts above yours. @RR30 and @boilerzz both share May 15th. It's always cool to find a birthday buddy.
I mentioned that there was a 50% chance that we get one match, with 23 responses. Took 32 responses to get a first match. But, only 37 responses to get a second match. 50% chance you get two matches with 45 responses, so we beat those odds.
Sometimes that's just the luck, or unluck, of the draw. If you know 500 people, there's going to be a few days in the year that have multiple birthdays - and a few that don't have any. If you ask around enough, I'm sure you can find someone. I know at least 5 people that share my birthday.
Devilz, what are the odds of going on a date with someone with the same birthday? 😆
Just an absolute shameless bday mention. Nothing to see here!
It is sweet.....Esp when we have our annual 4th of July gathering at my in-laws...Once people started realizing mt b-day was the 3rd, every gathering turned into Borden's fukin birthday bash....
Fukin, love it....BassPro gift cards all fukin day long...
I love Bass Pro Shops. I collect knives and there’s a knife that is exclusive to Bass Pro Shops that I plan to add to my collection at some point in the near future.
Say that to my students all the time.
Kidding. I love your post.
I just get stares, no laughs.
Memphis has an obscene BPS in the Pyramid. I'm not hunter/camper/shopper per se, but they have some pretty good restaurants and other things there that's pretty cool. There's a huge elevator in the middle that takes ppl to a deck at the point of the pyramid. They even have hotel rooms inside of the store and an underwater themed bowling alley, a good size pond that runs all through the main floor...etc.
It's kind of like a little village inside the pyramid.
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It figures you're the only one that would figure that out. I suppose that is why I Like you. Nah, really 19th.
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