I have a joint p.m.f. but am very stuck with how to find the following:

1) covariance

2) correlation coefficient of X and Y

3) If X and Y are independent

I already calculated the marginal p.m.f.s, means and variances from my data which is as follows:

x__ 1___ 2___ 3___ 4___ 5

y

3__.02_ .03_ .06__ .15_ .07

2__.02_ .05_ .08__ .12_ .06

1__.05_ .05_ .06__ .13_ .05