- #1

- 1

- 0

## Homework Statement

Let the random variables X and Y have the joint p.m.f.:

f(x,y) = (x+y)/32 x=1,2, y=1,2,3,4.

find the means [tex]\mu[/tex]

_{x}and [tex]\mu[/tex]

_{y}, the variances [tex]\sigma[/tex]

^{2}

_{x}and [tex]\sigma[/tex]

^{2}

_{y}, and the correlation coefficient [tex]\rho[/tex].

## Homework Equations

[tex]\rho[/tex]=(COV(X,Y))/[tex]\sigma[/tex]

_{x}[tex]\sigma[/tex]

_{y}

## The Attempt at a Solution

I was able to find both [tex]\mu[/tex]'s:

[tex]\mu[/tex]x= (25/16)

[tex]\mu[/tex]y= (45/16)

and both variances:

[tex]\sigma[/tex]

_{x}=(63/256)

[tex]\sigma[/tex]

_{y}=(295/256)

But I cant seem to find how to get the covariance...I tried just using the 1 and 2 values for x and y, but it hasn't worked. I think I'm getting confused because there are more y values than x values. Any help would be much appreciated!