It's not a paradox.
1. Leaving out the year opens the field a lot. Life expectancy is somewhere around 72 years.
2. About 350,000 people are born each day.
3. It's not about just my birthday. It's about each birthday in the group.
There are a fixed number of calendar days to be shared by an increasing number of people, which is well above that fixed number. There will be repeats.
12/13 - and I have family that shares a birthday with at least one of those listed - does that count?
5rd?
If you mean 1/5, that's my birthday, too.
10/19
It's not a paradox.
1. Leaving out the year opens the field a lot. Life expectancy is somewhere around 72 years.
2. About 350,000 people are born each day.
3. It's not about just my birthday. It's about each birthday in the group.
There are a fixed number of calendar days to be shared by an increasing number of people, which is well above that fixed number. There will be repeats.
paradox - a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true
Seems to fit. Besides, I didn't name it.
And I think you're missing the point here. Of course people share birthdays. This has nothing to do with population or life expectancy....just pure math. You could change the game from birthdays to any other measurable item, but any logical thinker would expect the number to be much higher than 57 before you're guaranteed a duplicate. If I told you there were 365 different words written on strips of paper in a hat and you pulled one at a time, wrote down the word and put the paper back in the hat, wouldn't you think the chances of you pulling the same word twice within the first 16 are pretty small?
Because that's what we did here. In fact, we've now hit 3 duplicates in 39 people. And that's before we even have a date for every month (still missing May and July).
No, MagicMatt has done it correctly, and his math is right. Year doesn't matter, just as if you have a random group of people you aren't trying to control for year.
Now, that said, what we're doing here isn't really random; we don't know how many people scan the thread and either do or don't post based on whether their birthday is listed or not. My birthday isn't listed so I'm not going to post it. There.
While it isn't a random sample nor a perfect test, that doesn't take away from the fact that MagicMatt is correct. <college professor here, who happens to teach statistics>
That's my wife's birthday (12/13) and my friend's birthday too....Just saying.
December 25
Out of more than six billion people, we're testing to see if a number of them share a very finite commonality; were more than one of them born on one of 365 days,...
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