In a school, there are 1000 students, out of which 430 are girls. It is known that out of 430, 10% of the girls study in class XII. What is the probability that a student chosen randomly studies in class XII given that the chosen student is a girl?

Let A be the event that a student chosen randomly studies in class XII and B be the event that the randomly chosen student is a girl.

We have to find P(A/B).

Clearly, n(A ∩ B) = 10% of 430 = 430 × (10/100) = 43

And, n(B) = 430

∴ Required Probability = P(A/B)

= n(A ∩ B) / n(B)

= 43 / 430

= 1 / 10