10th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    The mean of a data is 'p'. If each observation is multiplied by 3 and then 1 is added to each result, then the mean of the new observations so obtained is ___.      

    A)   \[p\]                           

    B)  \[3p\]                          

    C)  \[p+1\]          

    D)                     \[3p+1\]                    

    Correct Answer: D

    Solution :

    Given that, \[p=\frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+....+{{x}_{n}}}{n}\] or \[pn={{x}_{1}}+{{x}_{2}}+{{x}_{3}}+.....+{{x}_{n}}\] \[\Rightarrow \] \[3pn=3{{x}_{1}}+3{{x}_{2}}+3{{x}_{3}}+......+3{{x}_{n}}\] \[\Rightarrow \]\[3p=\frac{3{{x}_{1}}+3{{x}_{2}}+3{{x}_{3}}+.....+3{{x}_{n}}}{n}\]   ....(i)  Now, \[\frac{3{{x}_{1}}+1+3{{x}_{2}}+1+3{{x}_{3}}+1+....+3{{x}_{n}}+1}{n}\] \[=\frac{3{{x}_{1}}+3{{x}_{2}}+3{{x}_{3}}+....+3{{x}_{n}}+n}{n}\] \[=\frac{3{{x}_{1}}+3{{x}_{2}}+3{{x}_{3}}+....+3{{x}_{n}}}{n}+1\] \[=3p+1\]  [From (i)]


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