JEE Main & Advanced Sample Paper JEE Main Sample Paper-32

  • question_answer
                       The mean weight of 9 items is 15. If one more item is added to the series, the mean becomes 16. The value of 10th item is                       

    A) 35                          

    B)    30                 

    C) 25   

    D)    20      

    Correct Answer: C

    Solution :

    Let \[{{x}_{1}},{{x}_{2}},{{x}_{3}}\,.........,{{x}_{n}}\] are 9 items.                                \[\Rightarrow \,\frac{{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+\,.......{{x}_{9}}}{9}=15\]                 \[\sum\limits_{i=1}^{9}{{{x}_{i}}=135}\] If one more item \[{{x}_{10}}\] is added then                 \[\sum\limits_{i=1}^{9}{{{x}_{i}}=135+{{x}_{10}}}\] \[\therefore \] mean  \[\bar{x}\,=\frac{135+{{x}_{0}}}{10}=16\] \[\Rightarrow \,{{x}_{0}}=160-135=25\]


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