Question

An examination consists of two papers, Paper 1 and Paper 2. The probability of failing in Paper 1 is 0.3 and that in Paper 2 is 0.2. Given that a student has failed in Paper 2, the probability of failing in Paper 1 is 0.6. The probability of a student failing in both the papers is

• A. 0.5
• B. 0.18
• C. 0.12
• D. 0.06

Answer 1

The correct option is C 0.12

Let A and B be events of failing in paper 1 and paper 2 respectively.

P(A) = 0.3
P(B) = 0.2
P(A/B) = 0.6

Required probability

$=P(A\cap B)=P\left(A/B\right)P\left(B\right)=0.6\times 0.2=0.12$