# Ex 13.2, 7 - Chapter 13 Class 12 Probability

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 13.2, 7 Given that the events A and B are such that P(A) = 12 , P (A ∪ B) = 35 and P(B) = p. Find p if they are (i) mutually exclusive Given, P(A) = 12 , P (A ∪ B) = 35 and P(B) = p. Given sets A & B are mutually exclusive, So, they have nothing in common ∴ P(A ∩ B) = 0 We know that P(A ∪ B) = P(A) + P(B) – P(A ∩ B) Putting values 35 = 12 + p – 0 35 – 12 = p 6 − 510 = p 110 = p p = 𝟏𝟏𝟎 Ex 13.2, 7 Given that the events A and B are such that P(A) = 12 , P (A ∪ B) = 35 and P(B) = p. Find p if they are (ii) independent. Since events A & B are independent, So, P(A ∩ B) = P(A) P(B) = 12 × p = 𝑝2 Now, P(A ∪ B) = P(A) + P(B) – P(A ∩ B) Putting values 35 = 12 + p – 𝑝2 32 – 12 = p – 𝑝2 6 − 510 = 𝑝2 110 = 𝑝2 p = 210 p = 𝟏𝟓

Chapter 13 Class 12 Probability

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