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Birthday probability

Old 02-08-2006, 01:20 PM
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Default Birthday probability

If there are 23 people in a room the probability of 2 people sharing the same birthday is 50%. THT is a much larger group so lets put em up there.

03-09 for me



PS. Its pretty slow at work today. This might take us thru the winter.
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Old 02-08-2006, 02:00 PM
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Default Re: Birthday probability

11/07 for me ~




Is that CLOSE to 03/09.....?
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Old 02-08-2006, 02:27 PM
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04-18-19??............ and for my coming birthday I'd like.................I'll get back to you......
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Old 02-08-2006, 02:30 PM
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Default Re: Birthday probability

05/08

Mothers Day baby.


Taurus for those like to confirm I'm bull-headed
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Old 02-08-2006, 02:34 PM
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Default Re: Birthday probability

09/27

Its coming too fast.
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Old 02-08-2006, 02:40 PM
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Default Re: Birthday probability

8/5
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Old 02-08-2006, 02:44 PM
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Bailey Boat - 2/8/2006 1:27 PM

04-18-19??............ and for my coming birthday I'd like.................I'll get back to you......

04-18-19 Holy chit. I knew you were old, but d@mn

Oops! you just forgot the last 2 #'s....sorry lol.

1/21
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Old 02-08-2006, 02:47 PM
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Default RE: Birthday probability

byram - 2/8/2006 2:20 PM

If there are 23 people in a room the probability of 2 people sharing the same birthday is 50%. THT is a much larger group so lets put em up there.

03-09 for me



PS. Its pretty slow at work today. This might take us thru the winter.
I am trying to figure your math. 23 people and the probability of 2 having the same birthday is 50%? Wouldn't it be if 182.5 peole were in a room, the probability of 2 sharing the same birthdate would be 50%, correct?


Anyway mine is 03/20

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Old 02-08-2006, 02:52 PM
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Default RE: Birthday probability

Reel Boobs - 2/8/2006 3:47 PM

byram - 2/8/2006 2:20 PM

If there are 23 people in a room the probability of 2 people sharing the same birthday is 50%. THT is a much larger group so lets put em up there.

03-09 for me



PS. Its pretty slow at work today. This might take us thru the winter.
I am trying to figure your math. 23 people and the probability of 2 having the same birthday is 50%? Wouldn't it be if 182.5 peole were in a room, the probability of 2 sharing the same birthdate would be 50%, correct?


Anyway mine is 03/20


Opps, I was wrong! Byram you are correct! Heres how it is explained............

So, what is the probability that no two people will share a birthday?

Again, the first person can have any birthday. The second person's birthday has to be different. There are 364 different days to choose from, so the chance that two people have different birthdays is 364/365. That leaves 363 birthdays out of 365 open for the third person.

To find the probability that both the second person and the third person will have different birthdays, we have to multiply:

(365/365) * (364/365) * (363/365) = 132 132/133 225,
which is about 99.18%.

If we want to know the probability that four people will all have different birthdays, we multiply again:

(364/365) * (363/365) * (362/365) = 47 831 784/ 48 627 125,
or about 98.36%.

We can keep on going the same way as long as we want. A formula for the probability that n people have different birthdays is

((365-1)/365) * ((365-2)/365) * ((365-3)/365) * . . . * ((365-n+1)/365).
If you know permutation notation, you can write this formula as

(365_P_n)/(365^n).
That's the same as

365! / ((365-n)! * 365^n).


--------------------------------------------------------------------------------


We've made some progress, but we still haven't answered the original question: how large must a class be to make the probability of finding two people with the same birthday at least 50%?

We know that the probability of finding at least two people with the same birthday is 1 minus the probability that everybody has a different birthday, and we know how to find the probability that everybody has a different birthday for any number of people. The easiest way to find the right class size is to use a calculator to try different numbers in the formula. It turns out that the smallest class where the chance of finding two people with the same birthday is more than 50% is... a class of 23 people. (The probability is about 50.73%.)



D@mn, I hate being wrong!
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Old 02-08-2006, 02:57 PM
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3/30

On the probability part, 4 other of my friends have the same bday as I do. Needless to say, it was one fun 21st birthday party that many people do not remember.
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Old 02-08-2006, 02:58 PM
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Default Re: Birthday probability

2/21
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Old 02-08-2006, 03:04 PM
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Default RE: Birthday probability

Reel Boobs - 2/8/2006 1:47 PM

byram - 2/8/2006 2:20 PM

If there are 23 people in a room the probability of 2 people sharing the same birthday is 50%. THT is a much larger group so lets put em up there.

03-09 for me



PS. Its pretty slow at work today. This might take us thru the winter.
I am trying to figure your math. 23 people and the probability of 2 having the same birthday is 50%? Wouldn't it be if 182.5 peole were in a room, the probability of 2 sharing the same birthdate would be 50%, correct?


Anyway mine is 03/20

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Old 02-08-2006, 03:20 PM
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neckbone - 2/8/2006 1:57 PM

3/30

On the probability part, 4 other of my friends have the same bday as I do. Needless to say, it was one fun 21st birthday party that many people do not remember.
DING, DING, DING ... We have a winner!!

Mine too is 03\30!

The thirtyth birthday was kinda interesting.
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Old 02-08-2006, 03:23 PM
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msumoose - 2/8/2006 3:40 PM

8/5
8/5 - that makes a pair
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Old 02-08-2006, 03:26 PM
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There we go !! 2 matching pair
The younger person has to buy the older person a fishing lure. Age has its advantages .
are we having fun yet ?
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Old 02-08-2006, 03:27 PM
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thubert57 - 2/8/2006 4:20 PM

neckbone - 2/8/2006 1:57 PM

3/30

On the probability part, 4 other of my friends have the same bday as I do. Needless to say, it was one fun 21st birthday party that many people do not remember.
DING, DING, DING ... We have a winner!!

Mine too is 03\30!

The thirtyth birthday was kinda interesting.
Guess I need to get started on that batch of brew, so we'll have something to celebrate with.
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Old 02-08-2006, 03:28 PM
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02-07, yesterday and I celebrated with my doctor. He had fun by pulling my fingernail off. 9 months ago he put 3 screws in finger. Last month one of them worked its way out thru the nail, which caused the nail to become in-grown, which than became infected and swoll up to the size of a big toe on the end of my finger. I did get some great pain pills out the deal. He'd of never seen me if I knew he was going to do that.
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Old 02-08-2006, 04:01 PM
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Default Re: Birthday probability

9/23 here
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Old 02-08-2006, 04:24 PM
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06.03...yeah I have an evil twin...Gemini....Muuuuuwhaahaaahaaaa......
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Old 02-08-2006, 05:11 PM
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neckbone - 2/8/2006 2:27 PM

thubert57 - 2/8/2006 4:20 PM

neckbone - 2/8/2006 1:57 PM

3/30

On the probability part, 4 other of my friends have the same bday as I do. Needless to say, it was one fun 21st birthday party that many people do not remember.
DING, DING, DING ... We have a winner!!

Mine too is 03\30!

The thirtyth birthday was kinda interesting.
Guess I need to get started on that batch of brew, so we'll have something to celebrate with.
Yea, I need to break mine out too. A batch now would just be getting good about then. Maybe some Irish Red for a post St. Patty's Day event!

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