Two balls are drawn at random with replacement from a box containing 1

1.	Two balls are drawn at random with replacement from a box containing 10 black aid 8 red balls. Find the probability that (a) Both the balls are red.(b) One of them is black and the other is red
Answer» (a) P (both all red) \(=\frac{8}{18} \times \frac{8}{18}=\frac{16}{81}\) (b) P (one of them is black and other red) = P(First ball black, second red) or P (First red, second black) \(=\frac{10}{18} \times \frac{8}{18}+\frac{8}{18} \times \frac{10}{18}=\frac{20}{81}+\frac{20}{81}=\frac{40}{81}\)

Two balls are drawn at random with replacement from a box containing 10 black aid 8 red balls. Find the probability that (a) Both the balls are red.(b) One of them is black and the other is red

Answer»

(a) P (both all red) \(=\frac{8}{18} \times \frac{8}{18}=\frac{16}{81}\)

(b) P (one of them is black and other red) = P(First ball black, second red) or P (First red, second black)

\(=\frac{10}{18} \times \frac{8}{18}+\frac{8}{18} \times \frac{10}{18}=\frac{20}{81}+\frac{20}{81}=\frac{40}{81}\)

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Two balls are drawn at random with replacement from a box containing 10 black aid 8 red balls. Find the probability that (a) Both the balls are red.(b) One of them is black and the other is red

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