Conditional probability: A teacher gave his class two quizzes; 80% of the class passed the first quiz, but only 60% of the class passed both quizzes. What percent of those who passed the first quiz also passed the second quiz?

Question

turingtest · Answer

let A=first quiz is passed
let B=second quiz is passed
we then have that the probability of the second quiz being passed, given that the first is passed is$$P(B|A)=\frac{P(A\cap B)}{P(A)}$$

onepieceftw · Answer

Right, so 75% passed both quizzes

turingtest · Answer

well, no, it says in the problem that 60% passed both quizzes

onepieceftw · Answer

pardon me, 75% who passed the first quiz also passed the second

turingtest · Answer

correct :)

onepieceftw · Answer

Thanks a bunch!

turingtest · Answer

welcome!