This problem actually come up while ns was watching a show. I would assume the a probability check is come be offered here. It was observed is 21, if the expected is 12.5 questions. How would one go from here?

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Assuming each the answer to each inquiry is independently chosen, the answer have to be the number of ways we deserve to order 21 correct answers and also 29 incorrect answers.

A exactly answer has actually a probability that $1/4$ for an individual question, and $3/4$ for an untrue answer.

There space $50 choose 21$ methods to choose the 21 correct answers out of 50 questions. So the final probability need to be $$50 choose 21 (1/4)^21(3/4)^29$$This works out to about 0.3%

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You room taking a multiple-choice test through n concerns each the which has actually 4 alternatives. You have mastered 60% that the product

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