Question

If you make random guesses for 10 multiple choice SAT test questions (each with five possible answers), what is the probability of getting at least 1 correct? If these questions are part of a practice test and instructor says that you must get at least one correct answer before continuing, is there a good chance you will continue?

Answer 1

To calculate the probability of getting at least one correct answer out of 10 multiple choice questions with 5 possible answers each, subtract the probability of getting zero correct answers from 1.

Step-by-step explanation:

To calculate the probability of getting at least one correct answer, we can use the complement rule. The complement of getting at least one correct answer is getting zero correct answers. So, we need to calculate the probability of getting zero correct answers, and then subtract that from 1. The probability of getting zero correct answers in one question is 4/5, since there are 4 incorrect answers out of 5 possible choices. So, the probability of getting zero correct answers in 10 questions is (4/5)^10. Subtracting this probability from 1, we get the probability of getting at least one correct answer: 1 - (4/5)^10.