InterviewSolution
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InterviewSolution
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An instructor has a questionbank consisting of 300 easy True / False questions. 200 difficult True /False questions. 500 easy multiple choice questions and 400 difficultmultiple choice questions. If a question is selected at random from the |
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Answer» Clearly, the sample space cosists of 1400 quations. `:. n(S)=1400` Let `A=` event of selecting an easy question, and `B=` event of selecting a multiple - choice question. Then, `A nn B=` event of selecting an easy multiple-choice question. `:. n(A)=(300+500)=800, n(B)=(500+400)=900` and `n(A nn B)=500`. So, `P(A)=(n(A))/(n(S))=800/1400=4/7, P(B)=(n(B))/(n(S))=900/1400=9/14` and `P(A nn B)=(n(A nn B))/(n(s))=500/1400=5/14` Suppose b has already occurred and then A occurs. Thus we have to find `P(A//B)`. Now, `P(A//B)=(P(Ann B))/(P(B))=((5//14))/((9//14))=(5/14xx14/9)=5/9`. Hence, the required probability is `5/9`. |
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