A bowl with 10 marbles: 2 red marbles, 3 green marbles, and 5 blue marbles. We randomly select 4 marbles from the bowl, WITH REPLACEMENT, that is once a marble is selected, its color is noted and the marble is put back in the bowl (notice this does NOT resemble the hypergeometric distribution as that is without replacement).
(a) What is the probability of selecting 2 green marbles and 2 blue marbles?
(b) What is the expected number of green marbles?
(c) What is the covariance between Y1=the number of green marbles and Y2= the number of blue marbles?