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

  • question_answer
    Which of the following is correct?
    I. \[n(S\cup T)\] is maximum when n \[n(S\cap T)\] is least,
    II. If \[n(U)=1000,n(S)=720,n(T)=450,\] then least value of \[n(S\cap T)=170.\]

    A) Only I is true

    B) Only II is true

    C) Both I and II are true

    D) Both I and II are false

    Correct Answer: C

    Solution :

    [c]Both the statements are true. II. \[n(S\cup T)=n(S)+n(T)-n(S\cap T)\] \[=720+450-n(S\cap T)\] \[=1170-n(S\cap T)\] \[\Rightarrow 1170-n(S\cap T)\le n(U)\Rightarrow 1170-n(S\cap T)\le 1000\]\[\Rightarrow n(S\cap T)\ge 170\]


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