A speaks the truth in 75% cases whereas B lies in 20% cases . In what percent…
2025
A speaks the truth in 75% cases whereas B lies in 20% cases . In what percent of cases are they likely to contradict each other narrating the same incident ?
- A.
45%
- B.
35%
- C.
40%
- D.
30%
Attempted by 25 students.
Show answer & explanation
Correct answer: B
Let P(A speaks the truth) = 75% = 3/4, so P(A lies) = 1/4.
Let P(B lies) = 20% = 1/5, so P(B speaks the truth) = 4/5.
Case 1 (A lies, B truthful): (1/4) * (4/5) = 1/5 = 20%.
Case 2 (B lies, A truthful): (1/5) * (3/4) = 3/20 = 15%.
Total probability they contradict = 1/5 + 3/20 = 7/20 = 0.35 = 35%