Joint distribution (week 7)

Question 1

What does LIE mean of E(Y)?

Answer 1

E(E(Y|X))

Question 2

What if independent based on LIE?

Answer 2

E(XY) = E(X)E(Y)

Question 3

cov(aX +b, cY +d) =?

Answer 3

ac Cov(X,Y)

Question 4

how to find marginal given the PMF?

Answer 4

if cari marginal x, intergral to y

Question 5

what if marginal symmetry?

Answer 5

x and y are the same