Let $x_1, x_2,........,x_n$ be $n$ observations such that $\sum {{x_i}^2 = 300} $ and $\sum {{x_i} = 60} $ on value of $n$ among the following is

  • A

    $5$

  • B

    $10$

  • C

    $15$

  • D

    None of these

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class

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20-30

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Freq

1

3

4

2