Probability that A speaks truth is frac{4}{5} , while this probability for B is frac{3}{4} . probabi

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14.Probability

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The probability that $A$ speaks truth is $\frac{4}{5}$, while this probability for $B$ is $\frac{3}{4}$. The probability that they contradict each other when asked to speak on a fact

A

$\frac{4}{5}$

B

$\frac{1}{5}$

C

$\frac{7}{{20}}$

D

$\frac{3}{{20}}$

(AIEEE-2004) (IIT-1975)

Solution

(c) Here $P(A) = \frac{3}{4},\,P(B) = \frac{4}{5}$

$\therefore $ Required probability $ = P(A).P(\bar B) + P(\bar A)\,.\,P(B) = \frac{7}{{20}}$.

Standard 11

Mathematics

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