JEE Main & Advanced Sample Paper JEE Main - Mock Test - 19

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

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

    B)        \[|a-b|\]               

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

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

    Correct Answer: C

    Solution :

       [c] \[\sigma =\sqrt{\frac{\Sigma x_{1}^{2}}{2}-{{(\bar{x})}^{2}}}=\sqrt{\left( \frac{{{a}^{2}}+{{b}^{2}}}{2} \right)-{{\left( \frac{a+b}{2} \right)}^{2}}}\] \[=\sqrt{\frac{2{{a}^{2}}+2{{b}^{2}}-({{a}^{2}}+{{b}^{2}}+2ab)}{4}}=\frac{|a-b|}{2}\]       


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