Skip Navigation

Shared Birthdays

Travel Forums Off Topic Shared Birthdays


Last Post

11. Posted by Hien (Moderator 3906 posts) 11y

My birthday coincides with my parents' youngest child.

12. Posted by Wocca (Inactive 3745 posts) 11y

And are you the youngest child?

13. Posted by Cupcake (Travel Guru 8468 posts) 11y

1615 French explorer Samuel de Champlain discovers Lake Huron on his seventh voyage to the New World.
1794 Robespierre is beheaded in France.
1808 Sultan Mustapha of the Ottoman Empire is deposed and his cousin Mahmud II gains the throne.
1835 King Louis Napoleon of France survives an assassination attempt.
1868 The 14th Amendment to the Constitution, which guarantees citizenship to all those born or naturalized in the United States, is adopted.
1898 Spain, through the offices of the French embassy in Washington, D.C., requests peace terms in its war with the United States.
1914 Austria-Hungary declares war on Serbia, beginning World War I.
1920 Pancho Villa surrenders to the Mexican government.
1941 A Japanese army lands on the coast of Cochin, China (modern day Vietnam).
1945 A B-25 bomber crashes into the Empire State Building in New York City, killing 13 people.

Also born on this day
1844 Gerard Manley Hopkins, English poet and Jesuit priest.
1866 Beatrix Potter, children's author (The Tale of Peter Rabbit).
1887 Marcel Duchamp, French artist.
1902 Kenneth Fearing, poet and novelist (The Big Clock).
1927 John Ashbery, Pultizer Prize-winning poet (Self-Portrait in a Convict's Mirror).
1927 Baruch Blumberg, physician, medical researcher.
1929 Jacqueline Bouvier Kennedy Onassis, wife of President John F. Kennedy.

14. Posted by Wocca (Inactive 3745 posts) 11y

Probability of Shared Birthdays

There are 365 possible birthdays. (To keep the numbers simpler, we'll ignore leap years.) The key to assigning the probability is to think in terms of complements: "Two (or more) people share a birthday" is the complement of "All people in the group have different birthdays." Each probability is 1 minus the other.

a)What is the probability that any two people have different birthdays? The first person could have any birthday (p = 365¡Â365 = 1), and the second person could then have any of the other 364 birthdays (p = 364¡Â365). Multiply those two and you have about 0.9973 as the probability that any two people have different birthdays, or 1−0.9973 = 0.0027 as the probability that they have the same birthday.

b)Now add a third person. What is the probability that her birthday is different from the other two? Since there are 363 days still "unused" out of 365, we have p = 363¡Â365 = about 0.9945. Multiply that by the 0.9973 for two people and you have about 0.9918, the probability that three randomly selected people will have different birthdays.

c)Now add a fourth person, and a fifth, and so on until you have 22 people with different birthdays (p ¡Ö 52.4%). When you add the 23rd person, you should have p ¡Ö 49.3%.

d)If the probability that 23 randomly selected people have different birthdays is 49.3%, what is the probability that two or more of them have the same birthday? 1-0.493 = 0.507 or 50.7%. In a randomly selected group of 23 people, it is slightly more likely than not that two or more of them share a birthday.

15. Posted by areinstein (Travel Guru 2788 posts) 11y

Both my parents share the same birthday...but not the same year

16. Posted by tway (Travel Guru 7273 posts) 11y

I heard on the radio this morning that the BBC recently asked Bob Marley's fan club (??) if they could interview the singer for an upcoming documentary. I wonder what they replied? "Dear BBC, Bob's been pretty tight-lipped lately..."

Back to the topic! I share a May 15 birthday with:

  • James Mason
  • Josh Beckett

.. and a small list of people I've never heard of (who's Madhuri Dixit???)

17. Posted by Cupcake (Travel Guru 8468 posts) 11y

18. Posted by Isadora (Travel Guru 13926 posts) 11y

I share mine with (Aug 1):

Francis Scott Key
Herman Melville
Dom DeLuise (actor)
Yves St. Laurent
Jerry Garcia
Robert Cray (blues singer) (same year as mine)
Dhani Harrison (George Harrison's son)

First US census was completed on that date in 1790 - 4 million people

19. Posted by Wocca (Inactive 3745 posts) 11y

Quoting areinstein

Both my parents share the same birthday...but not the same year

I had parents-in-laws that shared the same birthday but in different years as well

20. Posted by Isadora (Travel Guru 13926 posts) 11y

Mr I's older brother and sister share the same month/day but different years. As do a cousin or two on his side.