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/sci/ - Science & Math

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981945 No.981945 [Reply] [Original]

Well?

>> No.981951

2 people

pending they are born on the same day

/thread

>> No.981957

1

>> No.981960

366 as there are 365 days in a year (leap year not included)

>> No.981965 [DELETED] 

If their brithdays are on random days 365.

Otherwise: 2.

>> No.981971

>Birthday paradox
look, he even have you a hint what you should google/search on wikipedia to solve this
what are you fags doing?

>> No.981975

There's never a 100% chance that two people share their birthday, assuming their birthdays are random.

>> No.981976

If their brithdays are on random days 365.

Otherwise: 2.

EDIT: make that 366.

>> No.981978

23 is 50%.
I forget what 100% is

>> No.981979

If you had statistics on every birthday, maybe it would be possible to get an answer.

>> No.981980

367

>> No.981981

23 people

>> No.981982

birthday paradox has nothing to do with 100% chance, for 100% you need to have 1 person for every possible birthday + 1

>> No.981983

Not 365, because even then some people can have birthdays together and days can be left out. This is a geometric distribution, therefore one can only derive, using limits, the EXPECTED number of people.

>> No.981984

Infinite.

You can never guarantee that two people will have the same birthday without a dependency.

However, all possibilities, including two people having the same birthday, become true in infinite people.

>> No.981988

23

>> No.981990

>>981980
sure is february 29 in that post

>> No.981993

>>981960

but one of them could be born in a leap year.

so to have a 100% probability you need 368 people

>> No.982005 [DELETED] 

>>981984

Thank you, for being the single person other than me in this thread knowing grade school statistics.

>> No.982001

>>981993
no no no. 366 days in leap year. +1 = 367

>> No.982003

>>981988
>>981981
that's only over 50% and not 100%, then

http://en.wikipedia.org/wiki/Birthday_paradox
http://en.wikipedia.org/wiki/Birthday_paradox
http://en.wikipedia.org/wiki/Birthday_paradox
http://en.wikipedia.org/wiki/Birthday_paradox
http://en.wikipedia.org/wiki/Birthday_paradox
http://en.wikipedia.org/wiki/Birthday_paradox

>> No.982006

>>981980

^This.

>> No.982013

>>981984
>>981983
>>981975
This. Except >>981984 has a flawed infinity concept.

>> No.982016

OP is a faggot that doesn't know how to phrase a question

>> No.982018

>>982013

I may have tweaked infinity over time...

Still works though.

>> No.982022

>>981975

Disregard this, after actually realizing what the question is, 366.

>> No.982027

367. Assuming it is possible for someone to have February 29th as a birthday.

Practically I'd say you need about 50, as a large portion of people are born in September.

>> No.982028

Omg sure that you are stupid...

just one.

>> No.982044
File: 125 KB, 614x427, rock_pigeon.jpg [View same] [iqdb] [saucenao] [google]
982044

The birthday paradox is for probabilities less than 100%. 100% is a special number, so you just need to apply the pigeonhole principle.

>> No.982046

367 is the correct answer.

>> No.982049
File: 3 KB, 245x241, 298.gif [View same] [iqdb] [saucenao] [google]
982049

>>982028
>implying one is at least two

>> No.982051

Assuming that humans have been on earth for 195000 years then this equals 71223750 days. Therefore we can say that you would need 71223751 people.

>> No.982108

>>982051
do dead people count as people?

>> No.982110

>>981983
>Not 365, because even then some people can have birthdays together and days can be left out.

do you realize that when those people have birthday's together that fulfills the requirement? idiot

>> No.982127 [DELETED] 

>1

>> No.982143

>>981983
lol'd

>> No.982159

>>981975
HUUUUUURRRRRRRGGGGGGGGGH

>> No.982162

1<

>> No.982169

It's solvable so it is not a paradox, is it?

>> No.982176

366

>> No.982181

Infinity.

>> No.982589

Get two people with the same birthday, lock them in a room together and there it is
100% chance they share a birthday

Or if you have 367 people in a room there is a guarantee two people share a birthday because there are only 366 days and the extra 1 person has to share a birthday with someone else

>> No.982599

>>982169

A paradox is a statement or group of statements that leads to a contradiction or a situation which defies intuition.

>> No.982602

the answer is the number of people who have the same birthday as the first person - the population of the earth.

>> No.982614

Haha, genius question to troll the "I've read about the Birthday Paradoxon on Wikipedia" people here, my congratulations.

>> No.982655

IT IS A POSSIBILITY THAT IN REAL LIFE YOU LOCK IN A ROOM LET SAY 500 RANDOM GENTLEMEN AND THAT NONE OF THEM WERE BORN ON OCTOBER 22.

THEN WE CAN ONLY ASSUME THAT AN INFINITE AMOUNT OF GENTLEMEN WOULD BE REQUIRED, UNLESS THE PEOPLE ARE CHOOSEN SO THAT THEY HAVE A WIDE RANGE OF BIRTHDATE.

>> No.982677

>>982655

If october 22 was omitted then another day most likely got overlapped.

>> No.982680

> at leaste two

>> No.982687

>>982655
but if none of them where born on October 22nd then two of them would have to share a birthday.

>> No.982699

if the room is a maternity ward.. i'd say 2.

>> No.982706

Infinite number of people

>> No.982757

366.
pigeonhole

>> No.982762

OP.

You must precise if a birthday is modulo 365,25 or not!

>> No.982767

Everybody put your birthday and we can find out.

22/06/87

>> No.982785

ugh people don't realize if 366 people are in a room 3 could all share a birthday :/

>> No.982791 [DELETED] 

>>982785
whoops. your correct. silly me

>> No.982797

look up pigeon hole for a 100% chance,
for less you can use approximations..

>> No.982807

730 or 732

>> No.982812

>>982767
22/06/87 here too wow

>> No.982813

>>982785

What?

>> No.982817

>>981945
367, includes all possible days (365 days in a year, plus Feb. 29 every 4 years, plus one more day so that at least one overlaps)
But more practically:

1 person.

Specifically, a women giving birth to twins.

>> No.982818

>>982812

WHAT? Me too! 22/06/87

>> No.982832

>>982817
That is three people.

>> No.982835

366 *2.

>> No.982843

>>982832
It's 1 person, then turns into 3 people, w/e.

>> No.982850

>>982843
>implying unborn children aren't people

>> No.982859

>>982843

Implying abortion is fine

>> No.982874

>>982859

Let's not go there.

>> No.982880

>>982850

they aren't according to the government

>> No.982896

>>981978

This is what it looks like when someone learns what the answer to a question is without understanding the question.

>> No.982906

>>982850
>>982859
>>982874
thread dereailed... i lol'd

>> No.982911

>>981978

if 23 =50%
then
46 = 100%

>> No.982916

>>982906
It's hardly derailed yet.

>> No.982917

>>982906
derailed- damn this laptop

>> No.982927

>>982911

Math does not work that way.

>> No.982940

>>982927

Multiply both sides by 2

>> No.982990

10.8 here

>> No.982995

>have a 100% chance
>limit as p approaches infinity is 100%
infinity

1/2/92

>> No.982998

>>982990
Edit. 10th of August

>> No.983010

INFINITY

>> No.983032

>>982818

Lol

But mine is 20-1

>> No.983033

>>982880

Which government?

>> No.983076

367.
I added one for 9th february.

>> No.983170

By pidgeonhole principle, you need 367 people to have a 100% that 2 have the same birthday.

>> No.983206

2

>> No.983230

>>983206

Correct

>> No.983238

UNPOSSIBLE

>> No.983246
File: 74 KB, 640x512, 1235421655368.jpg [View same] [iqdb] [saucenao] [google]
983246

/3/ is making a map of all the #chan network boards.

What does /sci/ want to look like?

>>>/3/92895

>> No.983310
File: 44 KB, 814x500, 10.jpg [View same] [iqdb] [saucenao] [google]
983310

Arguing about a middle school math exercise. Yeah, /sci/ is THAT pathetic.

367 people for a leap year.
366 people otherwise.

This is not a birthday paradox.

>> No.983354

>>983246

Shitdicks, wrong thing.

>> No.983378

Isn't it 23?

>> No.983420

doesnt matter as long as you have a pigeon

>> No.983442

>>981978
You can't get to 100%. Unless you can stuff an infinite amount of people in that room.

>> No.983484

>>983442

sci really is bad at mathematical problems. i wont even repeat the solution because it was mentioned so many times in this thread already.

>> No.983500

Anybody who said 365/366/367 are retarded.

>> No.983501

Everyone on sci is a self-proclaimed genius when in fact they know nothing of what they speak.

>> No.983512

>>982911
Heard of exponents?

>> No.983522

366 (no leap year) is correct

>> No.983524

>>983500

for all those that DON'T believe it's 366 or 367 people, then tell me what birthdays those 366 people could POSSIBLY have that would make it so all of them have DIFFERENT birthdays

>> No.983534

anyone who said 365/366/367/23 is fucking stupid. this is a hypothetical question, the real answer is infinite since you will never be able to know unless more information is given, as there will always be a probability.

or it could be 2, TWINS DURD UR DDURRRDRDRDR

>> No.983542

>>983534
dude there's 365 days, if you have more than that amount of people at least two share a birthday

>> No.983546

>>983524
Nowhere did OP state they had to have DIFFERENT birthdays.

Troll harder.

>> No.983547

>>983524

well 365 could have all the days this year and 366 could have feb 29th =p or we could mean birthday in the sense of year included too, but as there is an oldest person the maximal upper bound would still just be 365.25*n where n is the age of the oldest person in years, which is a finite number that we easily have within the world

>> No.983548

>>982818
HOLY SHIT ARE YOU ME?! I HAVE THAT SAME BIRTHDAY!

>> No.983549

Not counting retarded leap year bullshit, the answer is 366. Yes, it is 100%. The birthdays are random, and in the absolute worst case scenario, 365 people each have their birthday on a different day of the year, the 366th person must match one.

>> No.983555

>>983534
You're fucking retarded. If you have 366, it is possible that each person could have a different birthday. If you add one more, that person has to be sharing a birthday with someone considering that all the other possible days are already taken.

>> No.983559

>>983547

that's why I included 367 as well, to account for Feb. 29th

>> No.983566

This thread made me lose all hope in humanity.

>> No.983570

>>983566

I lost all hope in humanity the first day /sci/ became a board

>> No.983579

>>983566
that one about the boy and whether the other kid was a boy or girl was even worse.

>> No.983592

>>983570
The /adv/ board was the one that bothered me. "Hurr I'll ask /b/tards for advice" This will end well...

>> No.983594

>>983566

What do you think the answer is?

>> No.983596

More than you'll ever meet or make simple human contact with.

Also, INFINITE.

>> No.983606

>>983596

Idiot

>> No.983611

>>983596

Stop trolling already.

>> No.983615

>>983606
Troll harder.

>> No.983633

Do you mean birthday just by month and day, or by year as well?

>> No.983640

>>983633
Month and day.

>> No.983650

>>983640
makes sense.

>> No.983653

there are 365 dates on a one-year calender. birthdays do not include year, otherwise you would only have 1 birthday in your entire life.

That being said, 365 people in a room could all have a unique birthday in a typical, non-leap year. But when an additional person is added to the room, there is no date on which someone in the room does not already have a birthday.

Therefore 366 people are enough to guarantee at least two people share a birthday.

Q.E.F.D.

>> No.983654

>>981984
What birthday will the 366th person have that no one else has?

>> No.983656

>>983615
retard harder

>> No.983658

According to wiki it is 23

>> No.983664

Ok, too much trolling or stupidity in this thread. Time to clear some shit up.

OP is stating how much people need to be in a room for ANY TWO PEOPLE in the room to share a birthday. The answer for that is 366 or 367 (depending on leap year), because there are only 365/366 days in a year.

Some of you misinterpreted the question and thought OP wanted to know how much people are needed to have a 100% chance to have the same birthday as YOURSELF. In that case, it's infinity.

>> No.983666

There's never a 100% chance of anything happening ever.

>> No.983671

>>983666

so you're saying there's a 100% chance that there is never 100% chance of anything happening ever?

>> No.983672
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983672

>>981945
WHY DOES THIS THREAD HAVE 115 POSTS? FUCK YOU /SCI/.

FUCK YOU

>> No.983680

>>983666There's never a 100% chance of anything happening ever.

I suppose there's always the possibility that the earth's orbit will slow enough to add days to the year...

>> No.983687

If everyone is truly chosen at random then infinity.

>> No.983697

>>983687

HOW THE FUCK IS IT INFINITY!!!

>> No.983703

>>983671

Yes, so the statement is false, and there is a less than 100% chance of it happening. So it's true.

>> No.983710

>>983697
Bro, its not infinity, these assholes are trolling to get you pissed.

>> No.983712

never 100%

>> No.983721

>>983687
gtfo, please stop adding to the retard level of this thread.

>> No.983722

>>983703

there can't exist a system where every statement is false. if that were the case, then the statement "every statement is false" must be false as well, so there exists a true statement

>> No.983729

>>983697

the same reason people can't calculate a 20% tip on a $10 check. this is the sad world we live in.

>> No.983733

>>983729
it's $20, right?

>> No.983734

>>983729

Tip is 14%

>> No.983739

>>983734
A good tip is considered 15-20%, broseph.

>> No.983746

there are only 365 possible birthdays (fuck leap year)

So if there were 366 people in a room, at least one of them would have the same birthday as someone else.

>> No.983747

>>983739

and if you think your waiter deserves a "good tip" you're probably an annoying and/or demanding customer... seriously what is this shit, take an order bring food and recieve $10?

>> No.983753

goddamn leap years
always fucking up our shit

>> No.983758

My favorite thing about this thread is how everyone has typed "leapyear"

>> No.983759

>>983739
no a good tip is 21%
>i can 1-up you too!

>> No.983763

>>983747
By good tip I meant standard tip. Normal tip.

>> No.983770

I'm a Eurofag, after the exchange rate, what tip percent do I give?

>> No.983777
File: 48 KB, 470x600, Trollingbackinthedays.jpg [View same] [iqdb] [saucenao] [google]
983777

>>983770

>> No.983779

>>983770

nothing because you can get away with it without being considered an asshole, being foreign.

>> No.983800

Trick question. Its impossible because no statistic is has a 100% chance

>> No.983814

>>983800
>pigeonhole principle
fuck you

>> No.983816

>>983800
it's a 100% chance that you're a faggot.
use logic.

>> No.983823

>>983816

possibilities
1. he is a faggot
2. he is not a faggot

consider option 2 to be true for a moment, then he would not have made the post he did, therefor 1 must be true, and said poster is a faggot


guess your right

>> No.983830

OP worded his question vaguely specifically to troll.

>> No.983908

It isn't vague at all

Answer is 366 (no leap year)

>> No.983927

>>983908
If everyone is truly chosen random then their birthdays are.

>> No.983956

366.
While you CAN have two people with the same birthday with less people, it is not 100% certain until you exceed 365. There are only 365 different birthdays one can have (disregarding leap years), therefore if one has 366, then at least two will have to be sharing one.

>> No.983962

>>983927

Doesn't matter, only 365 days in a year. 366 means at least one repeats.

>> No.983977

>>983962
>>983962
Oh I was being an idiot nvm.

>> No.983984

>>983977

Respect

>> No.983994

>>983956
Thank you.

>> No.983998

>>983984
Just because we're anonymous doesn't mean we have to be jerks.

>> No.984001

>365 people in a room
>Guy walks in
>Someone asks what his birthday is
>"February 29th"
LOL

>> No.984011

>>983927If everyone is truly chosen random then their birthdays are.

Except that birthdays aren't random. More fucking and higher fertility in spring leads to more births in fall.

>> No.984015

the answer is 14

>> No.984016

It sure is idiot in here

>> No.984020

>>984001

LMAO

>> No.984022

I'm good.

>> No.984298
File: 51 KB, 367x451, 14.jpg [View same] [iqdb] [saucenao] [google]
984298

This discussion is full of faggots. You obviously don't know what 100% means.

Consider a room with 366 random people. Is there a 100% chance that at least 2 people there have the same birthday? No. There is a very very small chance that all people in that room have different birthdays, since there are 366 different possibilities (I'm counting February 29th). Only when we have more than 366 people. will there be a guarantee same-day birthday.

Weren't you faggots supposed to learn pigeonhole principle back in middle school? Fucking pathetic.

>> No.984303
File: 17 KB, 601x689, carlsagan2.jpg [View same] [iqdb] [saucenao] [google]
984303

2

starstuff, bitches

>> No.984360

366

>> No.984366

Lol. 365!....

>> No.984400

well you need 366+1 to include a leap year

>> No.984420

>>984303

I can't believe it took this long for someone to quote The Messiah.

THIS.

>> No.984425

>THIS THREAD
>MAKES ME
>VERY MAD

> : (