JEE Main & Advanced Sample Paper JEE Main - Mock Test - 29

  • question_answer
    If the arithmetic mean of the numbers \[{{x}_{1}},\,\,{{x}_{2}},\,\,{{x}_{3}}......{{x}_{n}}\] is \[\overline{x}\] then the arithmetic mean of numbers \[a{{x}_{1}}+b,\,\,a{{x}_{2}}+b\]+ b, \[a{{x}_{3}}+b,\,\,.......a{{x}_{n}}+b\], where a, b are two constants would be

    A) \[\overline{x}\]                        

    B)   \[na\,\overline{x}+nb\]

    C) \[a\,\,\overline{x}\]                              

    D) \[a\,\,\overline{x}+b\]

    Correct Answer: D

    Solution :

    Required mean \[=\,\,\frac{(a{{x}_{1}}+b)+(a{{x}_{2}}+b)+...+(a{{x}_{n}}+b)}{n}\] \[=\,\,\,\,\frac{a({{x}_{1}}+{{x}_{2}}+.....+{{x}_{n}})+nb}{n}\] \[=\,\,a\overline{x}+b,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( \because \,\,\,\frac{{{x}_{1}}+{{x}_{2}}+....+{{x}_{n}}}{n}=\overline{x} \right)\]


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