11th Class Mathematics Sample Paper Mathematics Olympiad - Sample Paper-7

  • question_answer
    If \[\overline{\mathbf{x}}\] is the mean of\[{{x}_{1}},{{x}_{2}},{{x}_{3}},.....{{x}_{n}}\]. Then the algebraic sum of the deviation about X is:

    A)  \[n\overline{x}\]                       

    B)  \[\frac{\overline{x}}{n}\]            

    C)  0                    

    D)  1

    Correct Answer: C

    Solution :

    [c] \[\because \overline{x}\]is mean of \[{{x}_{1}},{{x}_{2}}.{{x}_{3}},......{{x}_{n}}.\]. \[\therefore {{x}_{1}}+{{x}_{2}}+{{x}_{3}}+......{{x}_{n}}=n.\overline{x}\]  ......(1) Now, \[({{x}_{1}}-\overline{x})+({{x}_{2}}-\overline{x})+({{x}_{3}}-\overline{x})+.......({{x}_{n}}-\overline{x})\]              \[{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+......{{x}_{n}}-n.\overline{x}\] [from (1)] \[=n\overline{x}-n\overline{x}=0\]


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