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JEE Main & Advanced JEE Main Paper (Held On 8 April 2017)

  • question_answer
    The mean age of 25 teaches in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place. If now the mean age of the teachers in this school is 39 years, then the age (in years) of the newly appointed teachers is: [JEE Online 08-04-2017]

    A)  35                                         

    B)  40

    C)  25                                         

    D)  30

    Correct Answer: A

    Solution :

                    \[\frac{{{x}_{1}}+{{x}_{2}}+...+{{x}_{25}}}{25}=\overline{x}=40\]                 \[{{x}_{1}}+{{x}_{2}}+...+{{x}_{25}}=1000\]                 \[{{x}_{2}}+{{x}_{2}}+...+{{x}_{25}}=60+A=\overline{x}\times 25\]                 \[1000-60+A=39\times 25=975\]                 \[A=975-940=35\]


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