CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2001

  • question_answer
    If\[\mu \]is the mean distribution of\[\{{{y}_{i}},{{f}_{i}}\},\]then\[\Sigma {{f}_{i}}\{{{y}_{i}}-\mu \}\]is equal to:

    A)  MD                       

    B)         SD

    C)  0                            

    D)         relative frequency

    E)  none of these

    Correct Answer: C

    Solution :

    \[\because \]\[\mu \]is mean of distribution\[\{{{y}_{i}},{{f}_{i}}\}\]. \[\therefore \]\[\mu =\frac{{{y}_{1}}{{f}_{1}}+{{y}_{2}}{{f}_{2}}+....+{{y}_{n}}{{f}_{n}}}{{{f}_{1}}+{{f}_{2}}+.....+{{f}_{n}}}\] \[\Rightarrow \]\[({{f}_{1}}+{{f}_{2}}+.....+{{f}_{n}})\mu ={{y}_{1}}{{f}_{1}}+{{y}_{2}}{{f}_{2}}+...\]                                                                   \[+{{y}_{n}}{{f}_{n}}\] Now, \[\Sigma {{f}_{i}}({{y}_{i}}-\mu )=({{f}_{1}}{{y}_{1}}+{{f}_{2}}{{y}_{2}}+.....+{{f}_{n}}{{y}_{n}})\]                                                 \[-({{f}_{1}}+{{f}_{2}}+....{{f}_{n}})\mu \] \[=({{f}_{1}}+{{f}_{2}}+...+{{f}_{n}})\mu -({{f}_{1}}+{{f}_{2}}+....+{{f}_{n}})\mu \] \[=0\]


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