Question

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?

Answer 1

\[\text{ Suppose S represents a student chosen randomly studying in class XII and G represents a female student chosen randomly }  . \]

\[\text{ We have, } \]

\[P\left( G \right) = \frac{430}{1000} \]

\[P\left( S/G \right) = \frac{43}{1000}\]

\[\text{ Now } , \]

\[P\left( S/G \right) = \frac{P\left( S \cap G \right)}{P\left( G \right)} = \frac{\frac{43}{1000}}{\frac{430}{1000}} = \frac{1}{10}\]