10th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    The A.M. of 'n' numbers of a series is X. If the sum of first (n - 1) terms is 'k'. what is the\[{{n}^{th}}\] number?

    A) \[n\bar{X}-nk\]                

    B) \[n\bar{X}-k\]

    C) \[\bar{X}-nk\]                  

    D) \[\bar{X}-k\]

    Correct Answer: B

    Solution :

    Let the numbers be \[{{x}_{1}},{{x}_{2}},{{x}_{3}}.....{{x}_{n}}\].Then \[\overline{\text{X}}=\frac{1}{n}\sum\limits_{i=1}^{n}{{{X}_{1}}}\] \[\Rightarrow \] \[\overline{\text{X}}=\frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+.....+{{x}_{n-1}}+{{x}_{n}}}{n}\] \[=\frac{k+{{x}_{n}}}{n}[\because {{x}_{1}}+{{x}_{2}}+{{x}_{3}}+.....+{{x}_{n-1}}=k]\] \[\Rightarrow \] \[{{x}_{n}}=c\overline{\text{X}}-k\]


You need to login to perform this action.
You will be redirected in 3 sec spinner