A problem on a multiple-choice quiz is answered correctly with probability 0.9, given that a student prepared. an unprepared student guesses between 4 possible answers (so the probability of choosing

A problem on a multiple-choice quiz is answered correctly with probability 0.9, given that a student prepared. an unprepared student guesses between 4 possible answers (so the probability of choosing the correct answer is 1/4 for an unprepared student). seventy-five percent of students prepare for the quiz. if a student gives a correct answer to this problem, what is the probability that he or she did not prepare for the quiz?