JEE Main & Advanced Sample Paper JEE Main Sample Paper-28

  • question_answer
    The standard deviation of the numbers a and b is

    A)  \[\frac{\sqrt{{{a}^{2}}+{{b}^{2}}}}{2}\]                 

    B)  \[\frac{\left| a-b \right|}{2}\]  

    C)  \[\left| a-b \right|\]                                     

    D)  \[\frac{\sqrt{{{a}^{2}}+{{b}^{2}}}}{2}\]

    Correct Answer: B

    Solution :

    \[\sigma =\sqrt{\frac{\sum{x_{i}^{2}}}{2}{{(\overline{x})}^{2}}}=\sqrt{\left( \frac{{{a}^{2}}+{{b}^{2}}}{2} \right)-{{\left( \frac{{{a}^{2}}+{{b}^{2}}}{2} \right)}^{2}}}\] \[=\sqrt{\frac{2{{a}^{2}}+2{{b}^{2}}-({{a}^{2}}+{{b}^{2}}+2ab)}{4}}=\frac{|a-b|}{2}\]


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