# Example 16 - Chapter 13 Class 12 Probability

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Example 16 Bag I contains 3 red and 4 black balls while another Bag II contains 5 red and 6 black balls. One ball is drawn at random from one of the bags and it is found to be red. Find the probability that it was drawn from Bag II. Let E1 : Bag selected is bag 1 E2 : Bag selected is bag 2 A : Ball selected is Red B : Ball selected is Black We need to find P(ball was drawn from bag 2, if ball is red) = P(E2|A) We need to find, 𝑃 𝐸2|𝐴= 𝑃 𝐴 𝑃(𝐴|𝐸2)𝑃 𝐸1 𝑃 𝐴|𝐸1 + 𝑃 𝐸2 𝑃(𝐴|𝐸2) Putting values in formula, P(E2|A) = 12 × 511 12 × 37 + 12 × 511 = 12 × 511 12 [ 37 × 511 ] = 511 33 + 3577 = 511 6877 = 511 × 7768 = 3568 Therefore, required probability is 𝟑𝟓𝟔𝟖

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Chapter 13 Class 12 Probability

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About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.