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JEE Main & Advanced Mathematics Sets Question Bank Self Evaluation Test - Sets

  • question_answer
    Out of 32 persons, 30 invest in national savings certificates and 17 invest in shares. What is the number of persons who invest in both?

    A) 13

    B)                                15

    C) 17

    D)                                19

    Correct Answer: B

    Solution :

    [b]Let N = National savings certificates
    S = Shares
    Total no. of persons = 32
    No. of persons who invest in national
    Savings certificates = 30
    No. of persons who invest in shares = 17
    Therefore
    \[n(N\cup S)=32,n(N)=30,n(S)=17\]
    We know that,
    \[n(N\cup S)=n(N)+n(S)-n(N\cap S)\]
    \[\Rightarrow 32=30+17-n(N\cup S)\]
    \[\Rightarrow n(N\cap S)=47-32=15\]


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