Examples

Chapter 13 Class 12 Probability
Serial order wise

### Transcript

Example 4 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? Total number of students = 1000 Total number of girls = 430 Girls studying in class XII = 10% of 430 = 10/100 Γ 430 = 43 We need to find Probability that a student chosen randomly studies in class XII, given that the chosen student is a girl E: Student is in class XII F: Student is a girl We need to find P(E|F) Now, P(E β© F) = Probability student is a girl who is in Class XII = (ππ’ππππ ππ πππππ π π‘π’ππππ‘π  ππ πΆπππ π  " " ππΌπΌ)/(πππ‘ππ ππ’ππππ ππ ππ‘π’ππππ‘π ) = ππ/ππππ And, P(F) = Probability student is a girl = πππ/ππππ Now, P(E|F) = π(πΈ β© πΉ)/(π(πΉ)) = (43/1000)/(430/1000) = 43/430 = 1/10 = 0.1