b. The joint density of the continuous random variables X and Y is given by (f_{X,Y}(x,y) = kxy) for (0 leq x leq 1) and (0 leq y leq 1), and (f_{X,Y}(x,y) = 0) otherwise.
Find:
i. The value of k.
ii. (P(X leq y leq 3)).
iii. The marginal distribution and mean of X.
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