10th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    Mean of a certain number of observations is \[\overline{x}\]. If each observation is divided by \[m(m\ne 0)\] and increased by n, then the mean of new observations is ____.

    A)  \[\frac{\overline{x}}{m}+n\]                       

    B)  \[\frac{\overline{x}}{n}+m\]

    C)  \[\overline{x}+\frac{n}{m}\]                       

    D)   \[\overline{x}+\frac{m}{n}\]

    Correct Answer: A

    Solution :

    Let the observations be \[{{x}_{1}},{{x}_{2}},{{x}_{3}}.....{{x}_{r}}\] \[\Rightarrow \] \[\frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+....+{{x}_{t}}}{t}=\bar{x}\] Now, if each observation is divided by m and increased by n, then the new observations are  \[\frac{{{x}_{1}}}{m}+n,\,\,\frac{{{x}_{2}}}{m}+n......\frac{{{x}_{t}}}{m}+n\] \[\therefore \]    Mean of new observations \[=\frac{\frac{{{x}_{1}}}{m}+n+\frac{{{x}_{2}}}{m}+n+.....+\frac{{{x}_{t}}}{m}+n}{t}\] \[=\frac{\frac{1}{m}\,({{x}_{1}}+{{x}_{2}}+....+{{x}_{t}})+n\times t}{t}=\frac{{\bar{x}}}{m}+n\]


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