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JEE Main & Advanced Sample Paper JEE Main Sample Paper-34

  • question_answer
    In a set of 2n observations, half of them are equal to \[\alpha \] and the remaining half are equal to\[-\alpha \]. If the standard deviation of all the observations is 2, then the value of \[|\alpha |\] is equal to

    A)  2                                            

    B)  \[\sqrt{2}\]

    C)  \[2\sqrt{2}\]                     

    D)  4

    Correct Answer: A

    Solution :

    \[\mu (mean)=0\]             Standard deviation             \[=\sqrt{\frac{\sum\limits_{i=1}^{2n}{{{({{x}_{i}}-\mu )}^{2}}}}{2n}}\,\,\Rightarrow \,|\alpha |=2\]


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