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Subject: "Childbirth probability"     Previous Topic | Next Topic
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dale
guest
Aug-17-06, 07:29 PM (EST)
 
"Childbirth probability"
 
   What is the probability of a woman giving birth to 3 children and all of them born on the same day, but different years. So non-twins, non induced labor or planned c-section.


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  Subject     Author     Message Date     ID  
Childbirth probability dale Aug-17-06 TOP
  RE: Childbirth probability mr_homm Aug-17-06 1
     RE: Childbirth probability alexb Aug-18-06 2
     RE: Childbirth probability junglemummy Aug-30-06 3
  RE: Childbirth probability abhineetkaul Sep-01-06 4
     RE: Childbirth probability Silas Oct-06-06 5
         RE: Childbirth probability junglemummy Oct-11-06 6
             RE: Childbirth probability alexb Oct-11-06 7
         RE: Childbirth probability Ramsey2879 Oct-12-06 8
     RE: Childbirth probability manohar kaul Oct-22-06 9
  RE: Childbirth probability Chrissy May-24-07 10

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mr_homm
Member since May-22-05
Aug-17-06, 06:44 AM (EST)
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1. "RE: Childbirth probability"
In response to message #0
 
   Well the birth of the first child involves no coincidence whatsoever -- whenever you're born, that's your birthday.

The second child (assuming the birthday is determined randomly) has a 1/365 chance of having the same birthday as the first child, and the third has again a 1/365 chance of having that day as its birthday as well. Since the probabilities are independent, the chance of all three children sharing a birthday is 1/(365*365).

Hope this helps!

--Stuart Anderson


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alexb
Charter Member
2013 posts
Aug-18-06, 06:53 AM (EST)
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2. "RE: Childbirth probability"
In response to message #1
 
   There are too many unknowns to provide a definite answer.

Nothing is said about the parents' mating habits. It might be that they do it only on their birthdays and this only if the latter fall on full moon days. It may be that father held a job that took him far away from home with short sojourns with the family at the beginning of every spring. It may be that mother's body generated sperm antibodies all year round except when she suffered from early bloom allergies.

Then the probabilities will be much larger but depend seriously on random fluctuations around the expected delivery date.


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junglemummy
Member since Nov-7-05
Aug-30-06, 07:34 PM (EST)
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3. "RE: Childbirth probability"
In response to message #1
 
   Don't leap years affect this?


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abhineetkaul
Member since Sep-1-06
Sep-01-06, 07:34 PM (EST)
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4. "RE: Childbirth probability"
In response to message #0
 
   I am not sure if the probability of having second child is 1/365. That is possible only if it is certain that the second child will be conceived the next year i.e. the year of birth is definate. Too many assumptions need to be done.


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Silas
guest
Oct-06-06, 07:45 AM (EST)
 
5. "RE: Childbirth probability"
In response to message #4
 
   Not really - the dates are the same every year, and every year has 365 or 366 days in it. Even if it's two years later, three years later or ten years later, the birth of the third child only has a choice of 365 different dates to be born on (barring leap years). Therefore the chance of all three children being born on the same day is 1/365.25 * 1/365.25 (To average over a whole population.)

Say there are 10,000,000 sets of 3 siblings in the United States, then there are 75 where all three siblings have the same birthday.


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junglemummy
Member since Nov-7-05
Oct-11-06, 06:31 AM (EST)
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6. "RE: Childbirth probability"
In response to message #5
 
   I think you have hit the nail on the head, Silas. By looking at the families that already exist, instead of those where the children are yet to be born, it becomes a simple matter to work out the probability, because things like parents' mating habits etc don't have to be taken into consideration.


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alexb
Charter Member
2013 posts
Oct-11-06, 10:27 AM (EST)
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7. "RE: Childbirth probability"
In response to message #6
 
   I think there is an ambiguity in the question: "What is the probability of a woman giving birth ..."

One possibility is to interpret "a woman" as a generic reference to a child bearing representative of the human species.

Another possibility is to see in "a woman" an arbitrary but a fixed such representative.

Your reasoning applies within the first interpretation; mine with the second. You simply can't apply statistics to a specific person.


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Ramsey2879
guest
Oct-12-06, 10:36 PM (EST)
 
8. "RE: Childbirth probability"
In response to message #5
 
   Supposed the women had 9 children, wouldn't the probability be greater than if she had only 3?


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manohar kaul
guest
Oct-22-06, 08:43 AM (EST)
 
9. "RE: Childbirth probability"
In response to message #4
 
   This is possible depending upon the fertility of a woman also if she follows Chinese calender for conception which is having around 90 percent accuracy.Also she will have to go for c section to have birth on the same date but different year.


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Chrissy
guest
May-24-07, 08:15 AM (EST)
 
10. "RE: Childbirth probability"
In response to message #0
 
   I don't know about having '3' children on the same day but I have '2' children born on the same day 6 years apart. First child arrived 10 days after his due date. Second pregnancy the due date was my first childs birthday (which I was told would be unlikely as children hardly ever arrive on their due date) - but low and behold he made his entrance on that day!

Both born under the sign of 'Gemini' which is a sign of twins - both my boys are of a similar nature (I consider myself to have twins - just with a 6 year delay!)


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