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AP EAMCET2016MathematicsProbability

A speaks truth in 75 % of the cases and B in 80 % of the cases. Then, the probability that their statements about an incident do not match, is

Options

  1. A7 20
  2. B3 20
  3. C2 7
  4. D5 7

Correct answer

A. 7 20

Step-by-step solution

Let Event A: A speaks the truth Event B: B speaks the truth aligned & P(A)=75 %= 75 100 = 3 4 & and P(B)=80 %= 80 100 = 4 5 aligned Required probability aligned & P(A B )+P( A B)=P(A) P( B )+P( A ) P(B) & =P(A) [1-P(B)]+P(A) P(B) & = 3 4 (1- 4 5 )+ (1- 3 4 ) 4 5 & = 3 4 1 5 + 1 4 4 5 = 7 20 aligned

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