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Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-2

  • question_answer
    If the mean of the following data is 13.5, then the value of p is
    x 5 10 p 20 25
    f 10 10 10 2 8

    A)  15                   

    B)  150

    C)  10                   

    D)  None of these

    Correct Answer: A

    Solution :

    \[{{\mathbf{x}}_{\mathbf{1}}}\] \[{{\mathbf{f}}_{\mathbf{1}}}\] \[{{\mathbf{f}}_{\mathbf{1}}}\mathbf{\times }{{\mathbf{x}}_{\mathbf{1}}}\]
    5 10 50
    10 10 100
    p 10 10p
    20 10 40
    25 2 200
    \[\sum {{f}_{1}}=40\] \[\sum {{f}_{1}}{{x}_{1}}=10p+390\]
    \[\therefore \]      \[Mean\,\,\left( \overline{x} \right)=\frac{\sum {{f}_{1}}{{x}_{1}}}{\sum {{f}_{1}}}=\frac{10p+390}{40}\] \[\Rightarrow \]   \[13.5=\frac{10p+390}{40}\] \[\Rightarrow \]   \[13.5\times 40=10p+390\] \[\Rightarrow \]   \[540-390=100p\Rightarrow p=\frac{150}{10}=15\]


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