It has been noted that Roger Ebert and Paul McCartney were born on the same day (year, month and day). How many such coincidences should you expect?
To make things specific, assume there are 1000 celebrities of such stature and recency, and that whatever their average age is, the standard deviation of their ages is 12 years and follows a normal distribution. Of course the date is rounded to the day; don't worry about the hours.
Feel free to vary the assumptions for bonus answers.
1000/365 is about 3, meaning for any day of the year we'd expect about 3 celebrities both on that day. Suppose this to be the actual case.
Now we just need to find the chance of two with the same birthdate born in the same year.
Taking the standard deviation of 12 and a normal distribution, we can find the probability of a celeb being ...-3, -2, -1, 0, 1, 2, 3... years from the mean. Square these values to find the prob. that two random celebs are born in the same specified year. Add up this set of squares to find the total prob. I got about 0.0235
Since there are 3 celebs on each date, not two. We can multiply by 3 different pairings to get about 0.07
So every day there is about a 7% chance that two celebrities are sharing the same birthday.
Multiply this by 365 and you get about 25.7 such pairings per year.
Note the 1000 celebrities of stature is a tricky concept. The listing of famous birthdays every day is very large, but includes people I've never heard of. I found a listing for today, October 1 and has a includes a pair born on the same day but I am not familiar with the first:
Actor Yvette Freeman (“ER”) is 71. Actor Randy Quaid is 71.
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Posted by Jer
on 2021-10-01 09:00:11 |
Rough estimate
