Solve Probability Questions: Find E[X], E[2^X], & More

[sinyoungoh]

probability question please help!

i need full working out process...
thanks for helping me :)
1. Let X be a random variable with PMF
x 0 1 2 3 4
p(x) 5k 4k 3k 2k k

(a) Find k.
(b) Find E[X] and var(X).
(c) Find E[2^X].

2. The joint PMF of X and Y is pX;Y (x; y) = c(x2 + y2), x; y = 1; 2; 3. Find
(a) c and the marginal PMFs of X and Y
(b) E[X]
(c) The PMF of 3X - 2Y
(d) E[3X - 2Y ] in two ways.

 

[adriank]

This looks like homework, and thus belongs in a homework forum (read the stickies!)

Show us what you've attempted so far.