SOLUTION: a student takes an exam with 50 questions. Each question has 5 possible answers to choose from, with only one correct answer per questions. The student guesses on all 50 questions.

Question 510971: a student takes an exam with 50 questions. Each question has 5 possible answers to choose from, with only one correct answer per questions. The student guesses on all 50 questions. What is the probability the student guesses correctly on 20 or more questions?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
a student takes an exam with 50 questions. Each question has 5 possible answers to choose from, with only one correct answer per questions. The student guesses on all 50 questions. What is the probability the student guesses correctly on 20 or more questions?
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Binomial Problem with n = 50 and p(correct) = 1/5
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P(20<= x <= 50) = 1 - P(0<= x <=19) = 0.00093244
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Cheers,
Stan H.
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