9th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    The mean of n observation is X. If the first item is increased by 1, seconds by 2 and so on, then the new mean is

    A)  \[\overline{X}+n\]                    

    B)  \[\overline{X}+\frac{n}{2}\]          

    C)  \[\overline{X}+\frac{n+1}{2}\]   

    D)  None of these

    Correct Answer: C

    Solution :

    (c): \[\overline{X}={{x}_{1}}+{{x}_{2}}+{{x}_{3}}+....+{{x}_{n}}\](given) According to question New Mean=\[\frac{\left( {{x}_{1}}+1 \right)+\left( {{x}_{2}}+2 \right)+\left( {{x}_{3}}+3 \right)+...+\left( {{x}_{n}}+n \right)}{n}\]   \[=\frac{{{x}_{1}}+{{x}_{2}}+.....+{{x}_{n}}}{n}+\frac{1+2+3+.....+n}{n}=\overline{X}+\left( \frac{n+1}{2} \right)\]             


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