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ank0006
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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]2x and [tex]\sigma[/tex]2y, 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 can't 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!