Unusual birthday puzzle
 

This was posted on usenet a few years ago. Which of the following is more likely?

A) 365 random people have 365 different birthdays.
B) 365^2 random people don't have all 365 birthadys.

The probabilities are close. Ignore February 29th.

Re: Unusual birthday puzzle *DELETED*
 

Post deleted by random

Re: Unusual birthday puzzle
 

--deleted since what was once a question will now look like an unwarranted attack--

Re: Unusual birthday puzzle
 

aradsfa;lsk i'm retarded, 6am, going to sleep

Re: Unusual birthday puzzle
 

[ QUOTE ]
This was posted on usenet a few years ago. Which of the following is more likely?

A) 365 random people have 365 different birthdays.
B) 365^2 random people don't have all 365 birthadys.

The probabilities are close. Ignore February 29th.

[/ QUOTE ]

ok i am foolish enough to take a shot ( just like how i bluff the river with 8 high)
P(A) == 1/(365!)
P(B) >= 365*((364/365)^(365^2))

Am i close?
I will guess that B is more likely

Re: Unusual birthday puzzle
 

[ QUOTE ]
..will now look like an unwarranted attack

[/ QUOTE ] Certainly not. I said something stupid and it needed to be pointed out. I appreciate you deleting it, though. See ya.

Re: Unusual birthday puzzle
 

Well, they are close in order of magnitude. If anyone is
so inclined, they can check that the first probability is
roughly bigger by a factor of sqrt(2xpix365). (For those
who are mathematically inclined, it's almost immediate from
Stirling's approximation).

Re: Unusual birthday puzzle
 

im just curious, but how the hell did 2 pi get into a formula with 365 days?? [img]/images/graemlins/smile.gif[/img]

I should really learn this crap

Re: Unusual birthday puzzle
 

[ QUOTE ]
how the hell did 2 pi get into a formula with 365 days?

[/ QUOTE ]

Pi has nothing to do with the day count. Call it N days and then relate the 2 functions/series/whatever. That relation is where the guy is saying that pi comes from.

I don't know if he's right since I didn't investigate further, but that's what he means. I think.

~D

Re: Unusual birthday puzzle
 

Not a math guy but B
My guess would be that A isn't close.