00:01
Now, this problem, we've been given the following joint distribution for the variables, x, y, and z.
00:07
Now, our first task here is to find a marginal distribution of x and y.
00:14
Now, we're going to use the fact that these can be shown to be independent in order to break this up.
00:19
And so notice that we can write this as 4xy times 1 9th z squared.
00:29
Now, there's a reason i broke the 4 9th up in that manner.
00:32
And so that's so if we integrated z from 0 to 3, that would give us a value of 1.
00:40
And similarly, if we integrate 4xy over this entire square, we're both x and y are between 0 and 1, the interval of 4xy would also give us 1.
00:51
Now, having broken it apart like this, this tells us that our marginal distribution of x and y is equal to 4xy, or both x and y are between 0 and 1.
01:08
Now similarly on b, where we want the marginal distribution of 1, of z, and that's just this other piece out here.
01:16
And so this is one -ninth, z squared, where z is between zero and three.
01:23
And so this is our marginal distribution for z...