10th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    If the mean of first 'n' odd natural numbers is 'n' itself what is the value of 'n'?

    A)  2                                

    B)  3

    C)  1                                

    D)  Any natural number

    Correct Answer: D

    Solution :

    (d): Mean \[=\frac{1+3+5+7+......(2n-1)}{n}=n\] Or, \[[1+2+3+.....(2n-1)]\]\[-[2+4+6+....(2n-2)]={{n}^{2}}\] Or, \[\frac{(2n-1)(2n)}{2}-2[1+2+....(n-1)]={{n}^{2}}\] Or, \[n(2n-1)-\frac{2\times (n-1)n}{2}={{n}^{2}}\] Or, \[{{n}^{2}}={{n}^{2}}\Rightarrow \] for all natural numbers ?n? is true.


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