A multiple choice exam consists of 18 questions. Each question has three answers (i.e. A, B ve C). In every group of 6 consecutive questions, the correct answer of each question is followed by a different correct answer for the next question (e.g. if Q1 answer is A, Q2 answer should be either B or C). How many permutations of answers can you come up with? What is the probability that a student randomly guesses all answers correctly if he or she knows the pattern of correct answers described above.