An unprepared student takes a three-question, true/false quiz in which he guesses the answers to all thr?

1.)The student gets three answers wrong.


2.)The student gets exactly two answers correct.


3.) The student gets only the first acorrectnswerAn unprepared student takes a three-question, true/false quiz in which he guesses the answers to all thr?
Let C denote a correct answer and W a wrong answer.


There are 8 equally likely possible outcomes.


CCC


CCW


CWC


CWW


WCC


WCW


WWC


WWW


The probability of each possible outcome is 1/8.





So for your 1st question the probability of WWW is 1/8.





For your 2nd question consider CCW, CWC and WCC so the probability is 3/8.





For your 3rd question consider CCC, CCW, CWC and CWW, so the probability is 4/8 or 1/2.An unprepared student takes a three-question, true/false quiz in which he guesses the answers to all thr?
1/ (1/2)^3 = 1/8





2/ 3(1/2)^3 = 3/8





3/ (1/2)^3 = 1/8