Birthdays

14.04 MCs and Wizzs

Mine was two days ago, april 11th.
I'll celebrate it saturday

is this "mc" your sister, or the actual MC we have on this site?

28th of may

masterthief Conina is my sister....so itz the MC we have here...

twenty fifth of the eighth

+++October 3rd, which i hear is a holiday of some sort in germany!+++
+++they worship me!+++
+++Hexon+++

Well, they worship me, they just got the date wrong and are early a day..
So mine's on 4th of October.

October 3rd is indeed a holiday over here. We're celebrating the reunion of the two German states on that day and call it "Tag der deutschen Einheit", which means "day of German unity".

No they're not, october 4 is World Animal Day, remember?
Never mind, they used to tease me a lot with it when I was younger, because my birthday is october 3 as well, like Hexon's.
Quite a lot of people in the first week of october in the list right now, did you notice? Must be the best period to harvest the best Thud players.

Happy Thudding!

October 30th
so hopefully the whole october is good!

i like ham

don't we all

actually for some reason birthdays aren't a linear spread. if you get 365 ppl in a room the chances of two people having the same birthday are unexpectedly high. it's weird

it's math and it's logical

mathS

no, you can work out the probabilities of 365 ppl having 2 same b-days and test it and the real answer is WAY off

i.e. any 2 ppl have a 1 in 365.2575... chance of having the same b-day like 2 die with 365 sides but in reality the chances are like double that or something

although maths is logical but these godsdamn parametric matrices are getting on my nerves

Oh yes...er...what does this say???

P.S.:I don't like ham...I nearly hate it

12 jan...

24th November, but I'm here to add my weight to the maths problem

It's easiest to understand if you consider a group of perhaps 26 people* - a class in school, maybe. Now 26 dates spread out across 365, you'd expect it to be pretty unlikely that any two people would share a birthday, but in fact in most classes there'll be at least one pairing.

This is because you need to think about it differently:
Person A can be paired to any of the other 25 people, B-Z
Person B could be paired to A, but that's already been considered, so there are another 24 people, C-Z with which B could be paired.
C could be paired with 23
D with 22
etc...

When you do that for all the people in the room the number of pairings is 25+24+23+22+...+1 = 325
And that's enough pairings to get close enough to covering all the dates to explain the higher than expected number of shared birthdays.

At least, that's how it was explained to me a couple of years back, and it makes more sense than any other explanation.

Mr Scrub

wow,that's quite a hectic way of looking at it

but then what are the chances in the first place of a pairing occuring. you left out the possibility of A pairing with no-one.

You could also try and calculate the propability of "all 26 people have different birthdays".
I shall assume that each of the 365 days of the year has the same propability. (Makes calculations easier, but I don't think it really is. I also don't cover 29th of Feb.)
So for person A there are 365 possible days. Propability for the birthday is 1/365, then.
For person B there are only 364 days left (1 day already occupied by A). So propability rises to 1/364.
Overall propability is then: 1/365 * 1/364 * ... * 1/(365-25) = quite a low number. Just don't want to do the calculation.
So the propability of "at least 2 people sharing the same birthday" is quite high (near 1, which is the maximum possible).

I hope, I've got no error in this. Whoever finds one may keep it.

NO. NO. NO.

the probability for A having an unused b-day=365/365=1 because there are no taken b-days. therefore the chances of someone B NOT havoing the same b-day is 364/365 the prob of someone not having either is then 365 days minus the two used up=363/365

therefore the formula for n ppl not having the same b-day should be

summa n=1 to n [(365x365-1x365-2...x365-(n-1))/(365^n)]
so if the number of days is X and multiplication is *
summa n=1 to n [((X+1)-1)*((X+1)-2)*...*((X+1)-n) over 365^n]
therfore the probability of 0 overlaps among 365 ppl =a lot of number times 365-n which is 365-365=0 i.e. the probablility is =0 as it should be this should be able to be written better as:

{365! over (365-n)!} over 365^n

but it's undefined at n=365.

so the MATHEMATICAL probability of 28 ppl over-lapping at least once (as was the original example) = 1-P(no overlaps)

i.e. my calculator can't calc anything over 69! so what 365! is i have no idea wait it's 2.510412867555873228434144859674839360184e+778 so for 28 ppl the P is

365! over 337! over 365^28
1-P(28)=1-0.3455385276576006141954072736766079287918 IN THEORY
which is about 0.65 something...quite high actually.

in fact if the year were 50 days long then 28ppl is roughly 7.8% of 365 so we'd be MAYBE-MATHS ISN'T USUALLY SO LINEAR- looking at the probability of 4 ppl in 50 days over-lapping
= 50! over 46! over 50^4
=88.4% so I'd say that interestingly enough the previous stat is about right (the difference is prob due to EXCESSIVE rounding and the potential change of slope between the graphs

I AM A STUDENT OF SCIENCE SO I EMPLORE YOU ALL TO TRY AND FIND FAULT WITH MY WORK I DON'T WANT TO DISSENINATE NONSENSE OR TO DO INCORRECT CALCULATIONS

and THAT ladies and gentlemen is how wo do maths

Yes, that looks better. Thanks for the correction. My assumptions were wrong.

i actually don't really care all to much,frankly there is one guy in my class who's birthday is on mine,and 2 people who's birthdays are the day after,and my friend has the same birthday as his sister,and my mom has a birthday,and my dad has a birthday...

I think what we are talking about here is called the Birthday Paradox. It only states that the probability of two people having the same birthday is bigger once you have 23 or more, than the probability that all of them have a different one.

thanks OB,amkes much more sense now

but where's the fun in that? I was nonethless surprised at the results I got I mean for such a small amount of people to share a b-day with such a high probability.

and then if that's all it states it's not a paradox then. nyer nyer

well deal with it

you just don't appretiate maths

that's cos i mostly suck at everything other than the normal +-x%,that's a divide sign,i coul;dn't find anything else on the keyboard

All saints day (1 Nov)

O:-)

Mine is 15th of September.

heeeey twoflower! haven't seen you around these parts in ages! welcome back or i have i just been blind?

maybe you've poked your eye out with your pointy stick

oo look at the pretty list, a few birthdays are coming up soon.......

Angua

I saw we have a "MC" here too.... At this time I mean Masterthief Conina
of couse

Mine's July 24th.

29th of december 1992, twas a very good yeaaaaaaaaaar

Let me guess.....it was your Birthday?

Angua

i think she must be a soothsayer or something.

MAN YOUR SPOOKY. HOW DID YOU GUESS. SO WAS 1966. GUESS WHY.

noooo idea,give me a clue

Is it just me that finds this the most hilarious thread in quite a while?!? I mean what other forum are you going to find a disparate group of people form around the world arguing about how to calculate whether lotsa people share the same birthday

We seem to be blessed with an abundance of boffins, particularly mathematicians, and ones that are particularly amusing. Cheers folks, I've enjoyed the read

well i suppose it was a lucky guess

hmmm....let me think.....1966.....let me think...something about england and the world cup? against germany?

Angua

shame on me, i skipped them. i want my maths high to last a little bit longer. like, until tuesday.
my b-day is the 17th october...

happy b-day ponder and angua!!

yaaay thank yooou!

party party party!!

HAAAAAPPPYYYY BIRTHDAYYYYY!!!!

*Happy birthday to youuu,
happy birthday tooo youu!
Happy biiiirthday, Angua & Pondeeer!!
Happy birthday toooo youuuuuuuuu!!!*

We whish u2 many birthday presents and a really goooood party! I hope (for your parents) they made your favourite birthday cakes (*distrustful look at them*)!

Have a nice evening and... of cours: see u2 on thud!

masterthief Conina & little Wizzy

whoot thank you

i got load of prezzies ish lol, and i got a chocolate cake!!
am still trying to get a joint party sorted but its not going well cos the person who im having the joint pary with is away for aaaaages.

Also thanks Wizzy for the email very nice and BD for the PM
*feels special* lol

hehe
Angua

phew,still in time.

happy birthday angua,ponder,hope you have a great day/had a great day.ponder,when you read this tomorrow i expect you to have a pounding head and blurry eyes...angua,wait a couple of years.

sorry i didn't post earlier,working on sunday!!!

this place is more alive every day

hmmm....let me think.....1966.....let me think...something about england and the world cup? against germany?

Angua

okay. you are eally starting to freak me out now angua. i think she has physcic penguins like that pokemon. anyone remeber its name.

psychic penguins? sounds scary. lol