A test consists of 20 multiple-choice questions. Assume that a test taker randomly guesses a choice for each and every question, and each correct answer is worth 5 points. For problems 1 and 2 below, clearly state what probability model(s) you use and what value each parameter is equal to.
1. If each and every question has 3 choices (one correct, two incorrect), what is the probability that the test taker will get a B or better (i.e., 80 points or higher)?
2. If 18 questions has three choices each (one correct, two incorrect) and the remaining two are true-false questions (one correct, one incorrect), what is the probability that the test taker will get a B or better?