A​ multiple-choice exam has five possible answers for each question. For each correct​ answer, you are awarded 6 points. For each incorrect​ answer, 1 point is subtracted from your score. For answers left​ blank, no points are added or subtracted.   ​a) If you do not know the correct answer to a particular​ question, is it to your advantage to​ guess? Explain.   ​b) If you do not know the correct answer but can eliminate one possible​ choice, is it to your advantage to​ guess? Explain.