Question

the students answered a survey and the following information was obtained.

•70% of students regularly attended the classes.

•85% of students who attended the classes passed

.•40% of students who didn’t attend the classes failed.

Alice, a random students from that class, has passed this course. What is the probability that she has attended the classes?

Answer 1

Let: A be the event that a student regular attend the classees

Let: B be the event that a student passed.
We're given that students who regularly attended the classes passed, i.e.,

From the above two probabilities we can find-

Here we're also given that, 40% of students who didn't attend the class failed. i.e.,

From the above information we can find that,
Students who passed but didn't attend the class-

From the above information we can find-

  

Alice, a random students from that class, has passed this course.
The probability that she has attended the classes-

Alice, a random students from that class, has passed this course. The probability that she had attended all the classes is- 0.7677

I hope this clarifies your doubt. If you're satisfied with the solution, hit the Like button. For further clarification, comment below. Thank You. :)