An unprepared student must take a 7- question multiple-choice test that has 5 possible answers per question.

Question:

An unprepared student must take a 7- question multiple-choice test that has 5 possible answers per question. If the student can eliminate two of the possible answers on the first three questions, and if she guesses on every question, what is the probability that
(a) She will answer every question correctly?
(b) She will answer every question incorrectly?
(c) She will answer at least one question correctly?