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+--- Thread: Pi Notation Fun. (/showthread.php?tid=6181)
Pi Notation Fun. - Hazzy - 2008-12-10
My Stats teacher was talking about how a group of 23 people have a 50% chance of having at least two people in the group sharing a B-Day(Day and month, not year). I had seen a bit about summation and asked if there was a multiplicative(holy crap is that spelled right?) equivalent and I ended up with this.
![[Image: s6ktqp.gif]](http://i36.tinypic.com/s6ktqp.gif)
Assuming I didn't already know that it was 23 people, is there an easy way to find x other than churning out every value from 1 onward?
I scarcely remember reading about a formula or something for Sigma Notation...
Spoiler
Pi Notation Fun. - Fiel - 2008-12-11
They have the entire summation formula over at Wikipedia. Do a search for "Birthday Paradox" to get the formula.
Pi Notation Fun. - xpimnoob - 2009-01-02
you know whats more fun? probability of same day and year.
Pi Notation Fun. - Hazzy - 2009-01-02
xpimnoob Wrote:you know whats more fun? probability of same day and year.
But then you have to take into account the portion of the population that's age x.
I doubt there's the same amount of 42 year olds as 52 year olds.
