Thread: Conditional variance

If a matrix looks like this
.....-3 0 3 <-x
....0 0 0 0.2
y..1 0 0.2 0.1
....2 0.3 0.2 0


how do u calculate the variance for x, given y = 2?
How do u even find the probability function for x in this case with a conditional?

Do you know how to find the marginals of a Random Variable X (or Y)? What you want to do is not possible otherwise.

You mean the marginal probability? I think you sum the rows and columns in the 3x3 matrix to get that.