CBSE Class 12 Sample Paper for 2020 Boards

CBSE Class 12 Sample Paper for 2019 Boards →
Class 12
Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Question 26 - CBSE Class 12 Sample Paper for 2020 Boards - Solutions of Sample Papers and Past Year Papers - for Class 12 Boards

Last updated at July 25, 2026 by

A speaks truth in 80% cases and B speaks truth in 90% cases. In what percentage of cases are they likely to agree with each other in stating the same fact?

A speaks truth in 80% cases and B speaks truth in 90% cases. In what

Question 26 - CBSE Class 12 Sample Paper for 2020 Boards - Part 2

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Question 26 A speaks truth in 80% cases and B speaks truth in 90% cases. In what percentage of cases are they likely to agree with each other in stating the same fact? Given P(A speaks truth) = 80% = 80/100 = 8/10 P(B speaks truth) = 90% = 90/100 = 9/10 Now, P( both agree) = P(both speak truth) + P(both speak false) = P(A speaks truth) × P(B speaks truth) + P(A speaks false) × P(B speaks false) = 8/10 × 9/10 + (1−8/10)×(1−9/10) = 8/10 × 9/10 + (2/10)×(1/10) = 72/100 + 2/100 = 74/100 ∴ Percentage of cases where they agree is 74%

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