Forums

ForumsThe Tavern

Birthday list

Posted Dec 8, '12 at 7:18pm

Kasic

Kasic

5,746 posts

There's 74 users (including me, my birthday is 6/30/93) and there are two pairs of shared birthdays. According to Soccerdude's claim, we should have between 0 or 3 pairs at this point.

Small samples don't tell anything though.

 

Posted Dec 8, '12 at 8:14pm

rayoflight3

rayoflight3

440 posts

Soccerdude2's claim is, in theory, correct if we were to assume that each of the 365 days in a year (February 29 not included) had an equal number of birthdays of the people in this world. Other than that, it has nothing to do with statistics. It is a matter of probability.

The fact remains that your % chance of someone sharing a birthday with someone else in the room, assuming it is truly random, is 23/365, which is 6.3%.


No. I'm not sure how you came up with this, but this is not true.

To determine the probability in which no one in a room of 23 shares a birthday, let us consider each person separately and in order. Allow Person 1 to have any birthday (365/365). Now the probability for Person 2 to not share a birthday with Person 1 is (364/365). Similarly, the probability for Person 3 to not share a birthday with the former two is (363/365). Continue on and you get to Person 23 with 343/365. If we were to multiply this out, we would receive the probability in which no one shares a birthday, which equates to roughly 49.3%. Subtract from 1 (1 - .493), and we have 50.7%, the probability in which two or more people share a birthday in a room of 23 people.
 

Posted Dec 8, '12 at 11:01pm

Kasic

Kasic

5,746 posts

If we were to multiply this out, we would receive the probability in which no one shares a birthday, which equates to roughly 49.3%. Subtract from 1 (1 - .493), and we have 50.7%, the probability in which two or more people share a birthday in a room of 23 people.


Followed you up to here, and now I have absolutely no clue where you get 49.3%. 343/365 = .94 approximately, which means there's a 94% chance of not sharing a birthday, OR, conversely, a 6% chance of sharing...which is what I said earlier.

So yeah. Please elaborate on how you got 49.3% and 50.7%.
 

Posted Dec 8, '12 at 11:19pm

rayoflight3

rayoflight3

440 posts

Followed you up to here, and now I have absolutely no clue where you get 49.3%. 343/365 = .94 approximately, which means there's a 94% chance of not sharing a birthday, OR, conversely, a 6% chance of sharing...which is what I said earlier.


Sorry, I wasn't too clear. What I meant by "multiply this out" was this:

(1/365)^23 * (365*364*363...343) = .493

Here's the calculation on WolframAlpha to save you some time.
(Hopefully it shows up.)
 

Posted Dec 9, '12 at 11:15am

soccerdude2

soccerdude2

1,718 posts

Should there ever be any doubt in my claims?

Basically Kasic like rayoflight3 said you take the chance of someone not sharing a birthday with someone else (364/365) and then someone else not sharing a birthday with both of them (363/365) and so on (362/365)(361/365)(360/365)(359/365)...(343/365) and multiply them together to get the total chance of 23 people not sharing a birthday (49.3%). Subtract that from one and you get the opposite, the chance that someone shares a birthday with someone else in that room of 23 (50.7%).

The key is thinking of any person out of the 23 sharing a birthday with any other person out of the 23.

 

Posted Dec 25, '12 at 3:35pm

Blackbeltr0

Blackbeltr0

802 posts

Blackbeltr0: epiphany January 6

Found this thread thanks to 70_70_70

 

Posted Dec 26, '12 at 8:57pm

SaifurRahman

SaifurRahman

75 posts

My birthday was on October 5, 1999.

 

Posted Dec 26, '12 at 11:34pm

TheMostManlyMan

TheMostManlyMan

5,472 posts

Ernie15 - 1/5/1982
Blackbeltr0: - 1/6/????
IAgreeWithYou - 1/16/1998
Skeleton_Pilot - 1/18/1987
jeol - 1/23/1996
GhostOfHorror - 1/24/1999
Clancy12 - 1/25/1999
Gamecholic - 1/29/1994
xeano321 - 2/14/1996
zakyman - 2/14/1997
Star_shine - 2/24/1999
ShadowArchon - 2/27/1998
Salvidian - 2/29/1996
Max000_Extreme - 3/20/1999
Pedro97 - 3/21/1997
1zth - 3/22/1999
cje95 - 3/25/1995
ironblade41 - 4/1/1999
pangtongshu - 4/3/1995
Sauron23 - 4/10/1999
wflag10 - 4/14/1999
BRAAINZz - 4/19/1997
NoobSlayer3000 - 4/29/1997
IAgreeWithYou - 4/31/1998
killersup10 - 5/2/1999
nichodemus - 5/7/1994
Jefferysinspiration - 5/9/1991
Drink - 5/10/1994
ChillzMaster - 5/13/95
awesomeplayer312 - 5/14/1999
70_70_70 - 5/15/1991
psychoraven - 5/21/1998
Redslaughterer - 6/4/1999
Darkfire45 - 6/11/1996
partydevil - 6/17/1976
EmperorPalpatine - 6/20/1993
thebluerabbit - 6/21/1993
Kasic - 6/30/1993
Alpha791 - 7/2/1998
Alexandra222 - 7/3/1996
daleks - 7/6/1995
Kyouzou - 7/16/1994
MachineofLight - 7/17/1999
R2D21999 - 7/23/1999
feedback123 - 8/2/1990
MrDayCee - 8/5/1976
GhostOfMatrix - 8/10/1995
jezz - 8/19/1993
superdark33 - 8/30/1994
goumas13 - 9/7/1992
superbobdabest/superbob111 - 9/11/1999
soccerdude2 - 9/19/1997
StormWalker - 9/19/1998
AatosLiukkonen - 9/23/1996
Jeff1999 - 9/24/1999
BritHennerz - 9/24/1995
toemas - 9/26/1998
pickpocket - 10/1/??? (unknown millennium)
Skulltivator - 10/1/1992
SaifureRahma - 10/5/1999
fireangle - 10/6/1999
walshymusic - 10/18/1995
_Spaz_ - 10/21/1994
skydragon720 - 10/30/1998
mattzor - 10/30/1997
ImTheMostManlyMan - 10/31/1998
Tactical_Fish - 11/21/1996
Minotaur55 - 11/26/1997
xAyjAy - 11/27/1989
Gamer_Cale - 11/30/1994
alexandrica - 12/5/1999
Osumnis - 12/7/1997
dair5 - 12/18/1996
idigit - 12/21/1998
Armpit - 12/25/1980
Jacen96 - 12/27/1996

BlackBelt, please provide a year otherwise you will be deemed elderly.

 

Posted Dec 27, '12 at 6:32pm

TheMostManlyMan

TheMostManlyMan

5,472 posts

Here's an updated list doing what I should have done long ago, removing the innactive/banned. If you have been removed and would like that to change then just say so.


Blackbeltr0: - 1/6/????
IAgreeWithYou - 1/16/1998
Skeleton_Pilot - 1/18/1987
jeol - 1/23/1996
GhostOfHorror - 1/24/1999
Clancy12 - 1/25/1999
Gamecholic - 1/29/1994
xeano321 - 2/14/1996
zakyman - 2/14/1997
Salvidian - 2/29/1996
Max000_Extreme - 3/20/1999
Pedro97 - 3/21/1997
ironblade41 - 4/1/1999
pangtongshu - 4/3/1995
Sauron23 - 4/10/1999
IAgreeWithYou - 4/31/1998
killersup10 - 5/2/1999
nichodemus - 5/7/1994
Jefferysinspiration - 5/9/1991
ChillzMaster - 5/13/95
awesomeplayer312 - 5/14/1999
70_70_70 - 5/15/1991
Redslaughterer - 6/4/1999
partydevil - 6/17/1976
EmperorPalpatine - 6/20/1993
thebluerabbit - 6/21/1993
Kasic - 6/30/1993
Alexandra222 - 7/3/1996
Kyouzou - 7/16/1994
MachineofLight - 7/17/1999
R2D21999 - 7/23/1999
feedback123 - 8/2/1990
MrDayCee - 8/5/1976
GhostOfMatrix - 8/10/1995
jezz - 8/19/1993
goumas13 - 9/7/1992
superbobdabest - 9/11/1999
soccerdude2 - 9/19/1997
StormWalker - 9/19/1998
Jeff1999 - 9/24/1999
toemas - 9/26/1998
pickpocket - 10/1/??? (unknown millennium)
fireangle - 10/6/1999
walshymusic - 10/18/1995
skydragon720 - 10/30/1998
mattzor - 10/30/1997
ImTheMostManlyMan - 10/31/1998
Tactical_Fish - 11/21/1996
Minotaur55 - 11/26/1997
xAyjAy - 11/27/1989
Gamer_Cale - 11/30/1994
alexandrica - 12/5/1999
Osumnis - 12/7/1997
Jacen96 - 12/27/1996

 

Posted Dec 27, '12 at 8:39pm

winmaster1

winmaster1

649 posts

5/25 I DO NOT need you to know my age.

 
Reply to Birthday list

You must be logged in to post a reply!