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STD 11 - 14. probability — Maths STD 11 Science — Question

CBSE BoardEnglish MediumSTD 11 ScienceMathsSTD 11 - 14. probability1 Mark
MCQ
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
    $\frac{1}{5}$
  • ✓
    $\frac{7}{{20}}$
  • D
    $\frac{3}{{20}}$
✓

Answer

Correct option: C.
$\frac{7}{{20}}$
c
(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}}$.

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