# Ex 13.3, 2 - Chapter 13 Class 12 Probability

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 13.3, 2 A bag contains 4 red and 4 black balls, another bag contains 2 red and 6 black balls. One of the two bags is selected at random and a ball is drawn from the bag which is found to be red. Find the probability that the ball is drawn from the first bag. Let B1 : ball is drawn from Bag I B2 : ball is drawn from Bag II R : ball is drawn is red We need to find Now, Probability that ball is drawn from Bag I, if ball is red = P(B1 |R) So, P(B1 |R) = P 𝐵1 . P(𝑅| 𝐵1)P 𝐵1 . P(𝑅| 𝐵1)+P 𝐵2 . P(𝑅| 𝐵2) Putting values in formula, P(B1 |R) = 12 × 12 12 × 14 + 12 × 12 = 14 18 + 14 = 28 38 = 23 Therefore, required probability is 𝟐𝟑

Chapter 13 Class 12 Probability

Serial order wise

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Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.