20. The probability that a student will pass the final examination in both English and Hindi is and the probability of passing neither is . If the probability of passing the English examination is , what is the probability of passing the Hindi examination?
Let A be the event that the student passes English examination and B be the event that the students pass Hindi examination.
Given,
P(A)=0.75, P(A B) = 0.5, P(A' B') =0.1
We know,
P(A' B') = 1 - P(A B)
P(A B) = 1 - 0.1 = 0.9
Also,
P(A B) = P(A)+ P(B) - P(A B)
P(B) = 0.9 - 0.75 + 0.5 = 0.65
Hence,the probability of passing the Hindi examination is 0.65