Question
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.

Answer

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 $=\frac{8}{18}=\frac{4}{9}$
The ball is replaced after the first draw.
$​​​​​​\therefore\ $Probability of getting a red ball in the second draw $=\frac{8}{18}=\frac{4}{9}$
Therefore, probability of getting both the balls red $=\frac{4}{9}\times\frac{4}{9}=\frac{16}{81}$

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