# Probability

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 10 questions on the exam

b. Exactly 8 questions on the exam

c. At least 9 questions on the exam

https://brainmass.com/statistics/probability/calculating-probability-situation-combination-3503

#### Solution Preview

All the possibilities of choosing 10 questions out of 20 problems is 20!/(10!10!).

a. The student can answer all 10 questions, then the 10 questions are chosen from 15 problems that the student knows. There are totally 15!/(10!5!) choices. ...

#### Solution Summary

The solution addresses - 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 10 questions on the exam

b. Exactly 8 questions on the exam

c. At least 9 questions on the exam