00:01
The trip to this problem, why it's deceiving, is it's any two people can share the same birthday.
00:07
So it's not saying exactly two people like you sharing a birthday with somebody, and that's what deceives students.
00:14
So the thought process on this is that it's the complement of, let me write it this way, it's like the probability of the compliment of no shared birthdays.
00:29
And it's a complement of that because any two of them can share it.
00:33
So what we're going to do is one minus the probability of no shared birthdays.
00:41
And how do you figure out the probability of a shared birthday is basically, okay, well, the first person that we choose has 365 days to choose from, but they can have any of them.
00:54
But then the next person, they're still 365, you cannot share the same birthday.
00:59
It's the previous person, so it must be 364, and then continue this trend down, 363.
01:09
Dot, dot, dot, dot, until you get to the 12th person, shouldn't have made this look like a minus sign, but you continue to multiply until you get to the 12th person, and i would have to think about what that is, and then one minus that answer...