Using the same SAT questions described in Exercise 2, is 20 a significantly high number of correct answers for someone making random guesses?

Exercise 2

There are 80 questions from an SAT test, and they are all multiple choice with possible answers of a, b, c, d, e. For each question, only one answer is correct. Find the mean and standard deviation for the numbers of correct answers for those who make random guesses for all 80 questions.