If the records show that the probability of failing the course is 0.15, what is the probability that at most 2 students out of 20 fail this course?

If the records show that the probability for a student to get a grade B this course is 0.15, what is the probability that exactly 4 students out of 20 will have a grade B for this course?

What is the probability of selecting a grade A student for the first time either in 2nd or 3rd selection?

Grade Count

A 10

B 3

C 3

D 1

F 3