A biology instructor gives her class a list of eight study problems, from which she will select four to be answered on an exam.A student knows how to solve five of the problems.Find the probability that the student will be able to answer all five questions on the exam.

Question

Quizplus · Accepted Answer

There are 8 problems and 4 will be selected for the exam, so the total number of possible sets of problems is 8 choose 4 or 70. The student knows how to solve 5 problems, so the number of ways that the student can choose 4 out of those 5 problems is 5 choose 4, or 5. Therefore, the probability that the student will be able to answer all 5 questions is 5/70 or approximately 0.07, which is only possible in option B.

A Biology Instructor Gives Her Class a List of Eight