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Ex 13.2, 13 - Two balls are drawn at random from a box - Ex 13.2

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Slide34.JPG

  1. Chapter 13 Class 12 Probability
  2. Serial order wise
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Ex 13.2, 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. Two balls are drawn with replacement from a box Number of black balls in box = 10 Number of red balls in box = 8 Total number of balls in box = 10 + 8 = 18 P(both balls are red) = P(first ball is red) × P(second ball is red given first is red ) = 8﷮18﷯ × 8﷮18﷯ = 4﷮9﷯ × 4﷮9﷯ = 𝟏𝟔﷮𝟖𝟏﷯ Ex 13.2, 13 Two balls are drawn at random with replacement from a box containing 10 black and 8 red balls. Find the Probability that (ii) first ball is black and second is red. P(first ball is black & second is red) = P(first ball is black) × P(second ball is red given first is black) = 10﷮18﷯ × 8﷮18﷯ = 5﷮9﷯ × 4﷮9﷯ = 𝟐𝟎﷮𝟖𝟏﷯ Ex 13.2, 13 Two balls are drawn at random with replacement from a box containing 10 black and 8 red balls. Find the Probability that (iii) one of them is black and other is red. P(one ball is black & other is red) = P(first ball is black & second is red) + P(first ball is red & second is black) = 10﷮18﷯ × 8﷮18﷯﷯+ 8﷮18﷯ × 10﷮18﷯﷯ = 2 × 10﷮18﷯ × 8﷮18﷯﷯ = 𝟒𝟎﷮𝟖𝟏﷯

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