A question has possible answers. A student knows the correct answer with probability ; if she knows it she picks it, otherwise she guesses uniformly with probability each. Given that she picked the correct answer, the probability that she knew it is
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A question has m possible answers. A student knows the correct answer with probability p; if she knows it she picks it, otherwise she guesses uniformly with probability 1/m each. Given that she picked the correct answer, the probability that she knew it is (A) mp/[1+(m-1)p] (B) mp/[1+(1-p)m] (C) (1-p)/[1+(m-1)p] (D) (1-p)/[1+(1-p)m]
Probability and Bayes' theorem has come up 190 times in 7 exams since 2004.
This question is on Total probability and Bayes' theorem, part of Probability and Bayes' theorem in Statistics.
Reversing a conditional probability and updating beliefs from evidence.
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Question from the DSE 2020 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.