Quiz consists of 20 multiple choice questions, each with five possible answers, only one of which is correct. If a student guesses on each question, what is the mean and standard deviation of the number of correct answers?
mean: 4; standard deviation: 1.78885438
mean: 10; standard deviation: 1.78885438
mean: 4; standard deviation: 2
mean: 10; standard deviation: 3.16227766