A class is given a list of 20 study problems from which 10 will be part of an upcoming exam. If a given student knows how to solve 15 of the problems, find the probability that the student will be able to answer:
a. all ten questions on the exam
b. exactly eight questions on the exam
c. at least 9 questions on the exam

Question

A class is given a list of 20 study problems from which 10 will be part of an upcoming exam.  If a given student knows how to solve 15 of the problems, find the probability that the student will be able to answer:
a. all ten questions on the exam
b. exactly eight questions on the exam
c. at least 9 questions on the exam

anonymous · Answer

I think It is C.At least 9 questions on the exam (this may be wrong)

anonymous · Answer

@DarylDixonfan1, I am afraid this is not a multiple choice question. You are supposed to give an answer (the probability) for each one of the cases

anonymous · Answer

Same problem as having 20 balls in a box, out of which 15 are red. If we extract 10 balls without replacement, what is the probability of:
a)All ten balls are red
b)Exactly eight balls are red
c)At least nine balls are red

Use hypergeometric distribution function for this problem