00:01
In problem nine, we are looking at three different urns.
00:04
A, it has two whites, four reds, the probability of white there being one -third.
00:10
B has eight whites and four reds, the probability of white there being two -thirds, and then in the urn c, one white and three reds, probability of white there being a quarter.
00:21
Now, we want to find the probability that the first earn a produces a white, given the fact that there's exactly two whites chosen.
00:32
Now there's one ball chosen from every single one.
00:36
So just one from a, one from b, one from c.
00:38
What's the probability that a is white, given the fact that only two of the entire three selections are white.
00:48
So exactly two are white.
00:51
Well, in order to figure this out, because we're looking at a given, we want to know what is every single possibility of exactly two whites.
00:59
So if you look at a, b, and c, we want two whites.
01:02
We could have white, white, red.
01:04
We could have white, red, white, or we could have red, white, white.
01:08
These are all the possibilities of having exactly two whites.
01:12
We could look at this in terms of probability...