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JEE Main & Advanced JEE Main Paper (Held On 9 April 2017)

  • question_answer
    The sum of 100 observations and the sum of their squares are 400 and 2475, respectively. Later on, three observations, 3, 4 and 5, were found to be incorrect. If the incorrect observations are omitted, then the variance of the remaining observations is: [JEE Online 09-04-2017]

    A)  8.25                      

    B)  8.50

    C)  9.00                                      

    D)  8.00

    Correct Answer: C

    Solution :

      \[\sum\limits_{i=1}^{100}{xi=400}\]        \[\sum\limits_{i=1}^{100}{x{{i}^{2}}\,=2475}\] variance \[{{3}^{2}}+{{4}^{2}}+{{5}^{2}}\] \[9+16+25=50\] \[=\frac{2475}{97}-\,{{\left( \frac{388}{97} \right)}^{2}}\] \[\frac{2425}{97}-16\] \[\frac{2425-1552}{97}=\frac{873}{97}\] = (9)


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