Two balls are drawn at random with replacement from a box containing 10 black and 8 red balls. Find the probability that both balls are red-

16/81

Total number of balls = 18

number of red balls = 8

number of black balls = 10

Probability of getting a red ball in the first draw = 8/18 = 4/9

The ball is replaced after the first draw.

So, the probability of getting a red ball in second draw = 8/18 = 4/9

Therefore, the probability of getting both the balls red = (4/9) x (4/9) = 16/81