Use the at least once rule to find the indicated probability.
-An unprepared student makes random guesses on all questions of her multiple choice test. If there are 14 questions and each question has 6 possible answers, what is the probability she will answer
At least one question correctly?

Question

Quizplus · Accepted Answer

The probability of guessing at least one question correctly can be found by subtracting the probability of getting all questions wrong from 1. The probability of getting a question wrong is 5/6 (since there are 6 options and only 1 is correct). For 14 questions, the probability of getting all wrong is (5/6)^14. Thus, the probability of getting at least one right is 1 - (5/6)^14 ≈ 0.922.

Use the at Least Once Rule to Find the Indicated