JEE Main & Advanced Mathematics Statistics Question Bank Self Evaluation Test - Statistics

  • question_answer
    Let \[\bar{x}\] be the mean of n observations \[{{x}_{1}},{{x}_{2}},...{{x}_{n}},\]if \[(a-b)\] is added to each observation, then what is the mean of new set of observations?

    A) 0

    B) \[\bar{x}\]

    C) \[\bar{x}-(a-b)\]

    D) \[\bar{x}+(a-b)\]

    Correct Answer: D

    Solution :

    [d] Let \[\bar{x}\]is the mean of n observation \[{{x}_{1}},{{x}_{2}},...{{x}_{n}}.\] \[\Rightarrow \bar{x}=\frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+...+{{x}_{n}}}{n}\] Now (a - b) is added to each term. \[\therefore \] New mean \[=\frac{{{x}_{1}}+(a-b)+{{x}_{2}}+(a-b)+...+{{x}_{n}}+(a-b)}{n}\] \[=\frac{{{x}_{1}}+{{x}_{2}}+...+{{x}_{n}}}{n}+\frac{n(a-b)}{n}\] \[=\bar{x}+(a-b)\]


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