00:01
So let's talk about the difference between a permutation or a combination.
00:04
And a permutation order matters.
00:08
So here, selecting events a, b, and c, is different than selecting events b, a, than c, because the order here matters, whereas a combination, order does not matter.
00:20
So selecting events a, b, and c is the same as selecting events b and c.
00:25
So a nurse wants to visit nine patients all in one day.
00:29
Does the order matter here? yes, because she's going to see them regardless.
00:33
So there'd be one combination, but there's different permutations.
00:37
What is the permutation? well, what's the number of ways she can see the first patient? nine ways.
00:43
Second patient, okay, well, one's gone...