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Subject:
Probability of birthday in a group of 20 people
Category: Science > Math Asked by: francois777-ga List Price: $5.00 |
Posted:
09 Feb 2003 23:02 PST
Expires: 10 Feb 2003 06:05 PST Question ID: 159332 |
I see,b to recall from an old textbook that the probability to have at least one person having his/her birthday at a party attended by 20 people is about 50%. It was a fairly simple formula to derive that result but it has beeen 20 years... |
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There is no answer at this time. |
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Subject:
Re: Probability of birthday in a group of 20 people
From: j_philipp-ga on 10 Feb 2003 00:01 PST |
Hello Francois777, The following question is more common and known as the "Birthday Problem", and likely what you remember from the textbook. It's actually about the probability of two people sharing the same birthday on a party. Following page explains the calculation: The Birthday Problem http://members.tripod.com/%7EProbability/birthday.htm "If birthdays can be considered to occur at random, 23 guests are sufficient to ensure a 50% probability that at least two will have the same birthday." To many people, the number 23 is suprisingly low, and some would guess 183. The problem is also explained at the following page: Same.day http://rec-puzzles.org/new/sol.pl/probability/birthday/same.day And in this very complete article: Ivars Peterson's MathTrek - Birthday Surprises http://www.maa.org/mathland/mathtrek_11_23_98.html Related to that: Devlin's Angle http://www.maa.org/devlin/devlin_4_00.html You can find a list of all probabilities at: Birthday Probabilities http://tag.publication.org.uk/birthdays.php Hope it helps! Search terms: probability party birthday |
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