1.

The chance of a student passing an exam is 30% , the chance of a student passing the exam and getting above 80% marks in it is 10%, if it is given that a student has passed the examination, then find the probability that the student has secure more than 80% marks in the exam ?1. 3/82. 1/33. 1/94. 1/8

Answer» Correct Answer - Option 2 : 1/3

Concept:

P(A \(\cap\) B) = P(A) x P(B | A) = P(B) x P(A | B) where P(A | B) represents the conditional probability of A given B and P (A | B) represents the conditional probability of B given A.

Calculation:

Given: P(A student passing the exam) = 30% = 0.3, P(A student passing the exam and getting above 80% marks) = 10% = 0.1

The desired probability,

P(Student gets more than 80% marks | Student has passed the exam) = P(student passing the exam and gets more than 80% of marks) / P(Student has passed the exam)

⇒ P(Student gets more than 80% marks | Student has passed the exam) =  0.1/0.3

⇒ P(Student gets more than 80% marks | Student has passed the exam) =  1/3

Hence, option 2 is correct.



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