| jayno Posted on 14/1 14:09 | |
| when is your birthday | |
you need 23 people in a room,for two of the people to have the same birthday, so whens yours? | |
| ray192 Posted on 14/1 14:11 | |
| re: when is your birthday | |
16th Nov. | |
| the_broken_fridge Posted on 14/1 14:11 | |
| re: when is your birthday | |
6th Nov. | |
| baldycrowe Posted on 14/1 14:11 | |
| re: when is your birthday | |
Vladimir Lenin,thats all i have to say. | |
| newholgate Posted on 14/1 14:11 | |
| re: when is your birthday | |
23rd March | |
| jayno Posted on 14/1 14:12 | |
| re: when is your birthday | |
22nd june. | |
| john_lillie Posted on 14/1 14:14 | |
| re: when is your birthday | |
you need 23 people in a room,for two of the people to have the same birthday, so whens yours? That's a lie. There is a greater than 50% chance that a random selection of 23 people share a birthday. You'd need all 366 for it to be a certainty. | |
| Lockey_boro Posted on 14/1 14:14 | |
| re: when is your birthday | |
Aug 24th. | |
| paulo86 Posted on 14/1 14:16 | |
| re: when is your birthday | |
Aug 12th | |
| onthemap Posted on 14/1 14:16 | |
| re: when is your birthday | |
John that's not correct. You could have all 366 with the same birthday - just greater odds. | |
| jimmyrav Posted on 14/1 14:17 | |
| re: when is your birthday | |
Saturday! 20th jan 
| |
| jayno Posted on 14/1 14:17 | |
| re: when is your birthday | |
i beg to differ.What is the probability that in a room filled with 23 people at least two of them have the same birthday? (It's more than half!) jayno explains: The birthday problem asks how many people you need to have at a party so that there is a better-than-even chance that two of them will share the same birthday. Most people think the answer is 183, the smallest whole number larger than 365/2. In fact, you need just 23. The answer 183 is the correct answer to a very different question: How many people do you need to have at a party so that there is a better-than-even chance that one of them will share YOUR birthday? If there is no restriction on which two people will share a birthday, it makes an enormous difference. With 23 people in a room, there are 253 different ways of pairing two people together, and that gives a lot of possibilities of finding a pair with the same birthday. Here is the precise calculation. To figure out the exact probability of finding two people with the same birthday in a given group, it turns out to be easier to ask the opposite question: what is the probability that NO two will share a birthday, i.e., that they will all have different birthdays? With just two people, the probability that they have different birthdays is 364/365, or about .997. If a third person joins them, the probability that this new person has a different birthday from those two (i.e., the probability that all three will have different birthdays) is (364/365) x (363/365), about .992. With a fourth person, the probability that all four have different birthdays is (364/365) x (363/365) x (362/365), which comes out at around .983. And so on. The answers to these multiplications get steadily smaller. When a twenty-third person enters the room, the final fraction that you multiply by is 343/365, and the answer you get drops below .5 for the first time, being approximately .493. This is the probability that all 23 people have a different birthday. So, the probability that at least two people share a birthday is 1 - .493 = .507, just greater than 1/2.so there (pokes out tounge) | |
| john_lillie Posted on 14/1 14:20 | |
| re: when is your birthday | |
That's a lie. There is a greater than 50% chance that a random selection of 23 people share a birthday You said the same thing but in a much more long winded internet search | |
| john_lillie Posted on 14/1 14:21 | |
| re: when is your birthday | |
onthemap Posted on 14/1 14:16 Email this Message | Edit | Reply re: when is your birthday John that's not correct. You could have all 366 with the same birthday - just greater odds. You could do yes. but with 366 people (actually, it should be 367) there has to be a pair, thus it is a certainty. that's what the original post implied. | |
| jayno Posted on 14/1 14:22 | |
| re: when is your birthday | |
john,long winded internet search.this is something i have spent hours researching. | |
| onthemap Posted on 14/1 14:25 | |
| re: when is your birthday | |
John you are confusing probability with certainty. | |
| MontagueLongfellow Posted on 14/1 14:28 | |
| re: when is your birthday | |
WTF is this thread about ? | |
| baldycrowe Posted on 14/1 14:30 | |
| re: when is your birthday | |
It's about how old we are Funking ell  --- Post edited by baldycrowe on 14/1 14:31 --- | |
| jayno Posted on 14/1 14:32 | |
| re: when is your birthday | |
i am trying to win a bet. | |
| ayresomeangel365 Posted on 14/1 14:32 | |
| re: when is your birthday | |
wednesday.....all gifts gratefully accepted! | |
| baldycrowe Posted on 14/1 14:33 | |
| re: when is your birthday | |
How much where and when ? --- Post edited by baldycrowe on 14/1 14:33 --- | |
| john_lillie Posted on 14/1 14:36 | |
| re: when is your birthday | |
Mappy, I'm not. The opening post implied that with 23 people in a room that a pair would have the same birthday. This statement is incorrect there is only a slightly better than 50% chance of people sharing a birthday. for certainty, you must have at least 367 people in a room. | |
| jayno Posted on 14/1 14:36 | |
| re: when is your birthday | |
in the pub,with me mate,£20.he says something similar to john. | |
| onthemap Posted on 14/1 14:40 | |
| re: when is your birthday | |
John Let me first clarify one thing, you are saying that it is impossible to have more than 367 people in a room, without having two people sharing the same birthday? | |
| Smifter Posted on 14/1 14:41 | |
| re: when is your birthday | |
25th July | |
| wendymac Posted on 14/1 14:41 | |
| re: when is your birthday | |
August 12th same as paulo. | |
| Kidsbelly Posted on 14/1 14:42 | |
| re: when is your birthday | |
22 June | |
| baldycrowe Posted on 14/1 14:43 | |
| re: when is your birthday | |
So you think a chat room is a room! | |
| trodbitch Posted on 14/1 14:45 | |
| re: when is your birthday | |
John, are you on crack?  The probability of having two people in the same room share the same birthday >50% when there are 23 people. That said, you could still have 2 people in a room who both share the same birthday. You are saying that for it to be a "certainty", you have to have 366 people in the room. Wrong - you could have a billion people in the room and it would not be a certainty. It would be highly likely but that's not a certainty. | |
| trodbitch Posted on 14/1 14:45 | |
| re: when is your birthday | |
So you think this is a chat room? | |
| onthemap Posted on 14/1 14:51 | |
| re: when is your birthday | |
Thank you Trod. | |
| trodbitch Posted on 14/1 14:53 | |
| re: when is your birthday | |
Oh, 28th December
| |
| baldycrowe Posted on 14/1 14:53 | |
| re: when is your birthday | |
I said Trodders So you think a chat room is a room! 
| |
| Picol Posted on 14/1 14:56 | |
| re: when is your birthday | |
i thought everyone knew john's on steroids? surely crack would be too much of a chemical cocktail when mixed... | |
| burrah Posted on 14/1 14:57 | |
| re: when is your birthday | |
am i being dim? if there are 367 people in a room, and there are 366 different dates in a year, how could it be possible for at least 2 of them not to share the same birthday? not necessarily the same year, but that wasn't the initial question | |
| onthemap Posted on 14/1 14:57 | |
| re: when is your birthday | |
The queen has two birthdays so is she allowed in the room? | |
| trodbitch Posted on 14/1 15:02 | |
| re: when is your birthday | |
| You know what? I *am* the one on crack here! John is right! I am talking about birth dates, and he is on about birthdays. 367 people in a room and you are guaranteed two of them share a birthday. The version I have heard before is what are the chances someone else in the room will share a birthday with YOU and that isn't ever a certainty. Apologies John! | |
| MontagueLongfellow Posted on 14/1 15:04 | |
| re: when is your birthday | |
Mappy is the one on crack - FACT This thread makes me head hurt | |
| onthemap Posted on 14/1 15:12 | |
| re: when is your birthday | |
At least I can blame the crack eh Monty? | |
| MontagueLongfellow Posted on 14/1 15:17 | |
| re: when is your birthday | |
I dont know if Im thick or just have a low boredom threshold | |
| onthemap Posted on 14/1 15:19 | |
| re: when is your birthday | |
Clue- it's not your boredom threshold. | |
| baldycrowe Posted on 14/1 15:24 | |
| re: when is your birthday | |
How rude! | |
