Two balls are drawn at random with replacement from a box containing 10 black and 8 red balls. Find the probability that (i) both balls are red. (ii) first ball is black and second is red. (iii) one of them is black and other is red.

Question

$\begin{array}{1 1}(i) 10/18 (ii) 16/81 (iii) 40/80 \\(i) 16/81 (ii) 20/81 (iii) 40/81 \\(i) 4/81 (ii) 10/81 (iii) 20/81 \\ (i) 18/81 (ii) 18/81 (iii) 80/81 \end{array}$