InterviewSolution
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InterviewSolution
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In an entrance test, there are multiple choicequestions. There are four possible answers to each question, of which one iscorrect. The probability that a student knows the answer to a question is90%. If the gets the correct answer to a question, then find the probabilitythat he was guessing. |
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Answer» We define the following events: `A_(1):` He knows the answer `A_(2):` He does not know the answer `E:` He gets the correct answer Then, `P(A_(1))=9//10,P(A_(2))=1-9//10=1//10,` `P(E//A_(1))=1,P(E//A_(2))=1//4.` Therefore, the required probability is `P(A_(2)//E)=(P(A_(2))P(E//A_(2)))/(P(A_(1))P(E//A_(1))+P(A_(2))P(E//A_(2)))` `=(1/10xx1/4)/(9/11xx1+1/10xx1/4)=1/37` |
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