Let A denotes the event that students failed in physics.
According to question: 30% students failed in physics.
∴ P(A) = 0.30
Similarly, if we denote the event of failing in maths with B.
We can write that:
P(B) = 0.25
Also, probability of failing in both subjects can be represented using intersection as shown:
P (A ∩ B) = 0.1
Now we need find a conditional probability of failing of student in physics given that she has failed in mathematics.
We can represent the situation mathematically as-
P(A|B) =?
Using the fundamental idea of conditional probability, we know that:
Clearly our answer matches with option B.
∴ Option (B) is the only correct choice.
