Q.13    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.

Answers (1)

Two balls are drawn at random with replacement from a box containing 10 black and 8 red balls.

Total balls =18

Black balls = 10

Red balls = 8

The probability of getting a red ball in first draw 

                                                                            =\frac{8}{18}=\frac{4}{9}

The ball is repleced after drawing first ball.

The probability of getting a red ball in second draw 

                                                                            =\frac{8}{18}=\frac{4}{9}

the probability that both balls are red

                                                            =\frac{4}{9}\times \frac{4}{9}=\frac{16}{81}

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