Probability of birthdays on every day

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Discussion Overview

The discussion revolves around calculating the probability that in a randomly selected group of 430 people, there is at least one birthday on every single day of a 365-day year. The inquiry is framed within a statistical context, specifically exploring the assumptions of uniform distribution of birthdays.

Discussion Character

  • Mathematical reasoning
  • Exploratory
  • Debate/contested

Main Points Raised

  • One participant requests assistance in calculating the probability, emphasizing their lack of statistical skills and asking for a detailed explanation of the steps involved.
  • Another participant suggests that the question assumes a uniform distribution of births throughout the year, but raises concerns about the real-world applicability of this assumption due to factors like holidays and seasonal variations in birth rates.
  • A third participant confirms their interest in a mathematical approach that assumes even distribution of birthdays.
  • A later post identifies the problem as related to the "Coupon Collector's Problem" and references a formula for the probability, although the details of this formula are not provided in the discussion.

Areas of Agreement / Disagreement

Participants generally agree on the mathematical framing of the problem, but there is disagreement regarding the assumptions of uniform distribution and its relevance to real-world scenarios.

Contextual Notes

The discussion does not resolve the assumptions regarding the distribution of birthdays or the applicability of the mathematical model to real-world data.

duzza275
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Please may someone help me with this and if you have an answer please may you show all the steps that you took. This is not a prep question but I was thinking about it and wondering what the answer was but my statistics skills are not good enough for this yet. :)

If I have a randomly selected group of 430 people. What is the probability that there is 1 birthday on ever single day in the year? (Assume that it is a 365 day year)

Thanks
 
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Good luck...I guess you are asking for an answer from the purely mathematical point of view assuming a uniform distribution of births throughout the year?

I am wondering because that's not what REALLY happens. Weather and holidays affect love-making; last I heard, new year's is a 'lucky' day and so, we have a lot of September people.

Just look at the animal kingdom; ok, they don't have holidays, but look at how the times when, basically, the entire group gives birth within a matter of days or weeks ruled by migratory patterns, availability of food, weather conditions, etc.

Anyway, just a thought.
 
Yeh I am looking for an answer with a mathematical point of view that assumes that births are evenly distributed throughout the year.
 
duzza275 said:
Please may someone help me with this and if you have an answer please may you show all the steps that you took. This is not a prep question but I was thinking about it and wondering what the answer was but my statistics skills are not good enough for this yet. :)

If I have a randomly selected group of 430 people. What is the probability that there is 1 birthday on ever single day in the year? (Assume that it is a 365 day year)

Thanks

This is the "Coupon Collector's Problem". See my reply to this post

https://www.physicsforums.com/showthread.php?t=523620

for a formula for the probability.
 

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