1. If the discrete random variable X has a probability distribution: X 0 2 4 8 P(X) 1/4 1/2 then P(X=2 or 8)= 2. Which of the following random variables follows a binomial distribution? A bag contains only red and green marbles. Drawing a marble at random from the bag without replacement 7 times, and let x be the number of green marbles obtained. Rolling a die 6 times, let x be the number of prime numbers observed. Tossing a coin, let x be the number of times needed to get a head for the first time. A test contains 5 true/false questions and 5 multiple choice questions, where each question has 5 selections. Answering all questions by random guessing, and let x be the number of correct answers obtained. A bag contains only red and green marbles. Drawing a marble at random from the bag with replacement 5 times, and let x be the number of red marbles obtained