A professor has learned that three students in his class of 20 will cheat on the final exam. He decides to focus his attention on four randomly chosen students during the exam. What is the probability that he finds at least one of the students cheating?
A) 0.4912
B) 0.4211
C) 0.5088
D) 0.5789

Question

Quizplus · Accepted Answer

The probability that none of the four chosen students will cheat is (17/20)x(16/19)x(15/18)x(14/17) = 0.4912. Therefore, the probability that at least one of the four chosen students will cheat is 1-0.4912 = 0.5088.

A Professor Has Learned That Three Students in His Class