Given two lists of different size, find E(XY)

1. The problem statement, all variables and given/known data

I'm given list x, with 8 elements. List y, with 10 elements. Find expectation and variance of x,y,x+y,xy





2. Relevant equations







3. The attempt at a solution

E(x), E(y), E(x+y), var(x),var(y) are all straightforward. But how do I find E(xy)? Do I just have to multiply out everything? Then I would need to find mean and variance of a sample set of 80. Is there an easier way?



I am given literally no information about the numbers. Not what they represent, if they're related, nothing.