Find mean and variance of X and Y

[phillyolly]

Homework Statement

I have found the marginal distribution for X and Y from a table. (No statistical regression, just simple table)
How should I proceed in finding mean, variance an correlation coefficient of X and y? I am computing by hand.
Thank you,

Homework Equations

The Attempt at a Solution

 

[phillyolly]

Is mean for X:

(1/8+3/8+3/8+1/8)
-------------------
4

and mean for Y is

(2/8+4/8+2/8)
--------------
3

?

 

[vela]

No. Remember the mean of a random variable is defined as

$$\bar{X} = \sum_i x_i P_X(x_i)$$

It's the sum of the product of the values X can take on multiplied by probability of that value.