A​ multiple-choice test has
six possible answers for each question.

​(a) If a student guesses at the​ answer, what is the probability that he or she selects the correct answer for one particular​ question?

​(​b) If the student first eliminates
one of the six possible answers and guesses from the remaining​ possibilities, what is the probability that he or she selects the correct answer to that​ question?