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Questions › DSE › DSE 2004 › Q26
2 marks, −1Statistics › Probability and Bayes' theorem › Total probability and Bayes' theoremModerateabout 3 min

DSE 2004 Question 26: Probability and Bayes' theorem

Consider an examinee answering a multiple-choice examination. For a particular question with 444 choices, the probability that the examinee knows the answer is 1/31/31/3, the probability that she makes the correct choice given that she knows the answer is 111, and the probability that she makes the correct choice given that she does not know the answer is 1/41/41/4. The probability that she knew the answer given that she has made the correct choice is

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Plain-text version

Consider an examinee answering a multiple-choice examination. For a particular question with 4 choices, the probability that the examinee knows the answer is 1/3, the probability that she makes the correct choice given that she knows the answer is 1, and the probability that she makes the correct choice given that she does not know the answer is 1/4. The probability that she knew the answer given that she has made the correct choice is (A) 1/3 (B) 3/4 (C) 2/3 (D) 5/6

Probability and Bayes' theorem has come up 190 times in 7 exams since 2004.

What this question tests

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.

TestStop has 22 past-paper questions on this subtopic.

Practise Probability and Bayes' theoremMore on Total probability and Bayes' theorem

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Question from the DSE 2004 paper. Solutions are TestStop's own. Not affiliated with or endorsed by any examination authority.