Math Help - Covariance Question?

1. Covariance Question?

Discrete random variables X and Y have joint probability mass function given by
 Y=1 Y=2 Y=3 Y=4 x=2 0.25 0.25 0 0 x=4 0 0 0.25 0.25

What is the Covariance of this question? Can anyone help?

2. Re: Covariance Question?

Well there's the formula for the covariance I think its just a matter of plugging in the appropiate terms.. I could be wrong here tho. $cov(xy)=\frac{1}{N}\sum(x_i - \bar{x})(y_i - \bar{y})$. Hope this helps even a little.

EDIT: here's exactly what your looking for good luck.https://onlinecourses.science.psu.edu/stat414/node/109

- JoeDIT