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Probability

Question
CBSEENMA12033594

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?

Solution
Let E denote the event that a student chosen randomly studies in class XII and F be the event that the randomly chosen student is a girl.
Total number of students = 1000
Number of girls = 430
Number of girls studying in class XII = 10 over 100 cross times 430 space equals space 43
Now, P(F) = 430 over 1000 space equals space 0.43  and straight P left parenthesis straight E intersection straight F right parenthesis space equals 43 over 1000 space equals 0.043
therefore space space space straight P left parenthesis straight E space left enclose straight F right parenthesis space equals space fraction numerator straight P left parenthesis straight E space intersection thin space straight F right parenthesis over denominator straight P left parenthesis straight F right parenthesis end fraction equals space fraction numerator 0.043 over denominator 0.43 end fraction space equals fraction numerator begin display style 43 over 1000 end style over denominator begin display style 43 over 100 end style end fraction equals space 43 over 100 cross times 100 over 43 space equals 1 over 10 space equals space 0.1

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