5 An urn contains 10 red balls and 30 blue balls.

a Suppose you draw 4 balls from the urn. Let Xi be the number of red balls drawn on the ith ball (Xi = 0 or 1). After each ball is drawn, it is put back into the urn.

Are the random variables X1, X2, X3, and X4 independent random variables?

b Repeat part

(a) for the case in which the balls are not put back in the urn after being drawn.