SOLUTION: An unprepared student makes random guesses for 6 multiple choice questions that have selections a - e. Find the probability that there is at least one correct answer
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Question 321724: An unprepared student makes random guesses for 6 multiple choice questions that have selections a - e. Find the probability that there is at least one correct answer Answer by solver91311(24713) (Show Source):
The probability of successes in trials where is the probability of success on any given trial is given by:
Where is the number of combinations of things taken at a time and is calculated by
The probability your student got at least one correct is equal to 1 minus the probability that he missed them all, which is to say 1 minus the probability that he got zero correct. You want the probability of zero successes in six trials where the probability of success on a given trial is one-fifth, or 0.2.
You get to do your own arithmetic. Hint: for all positive integers .
