If mean and standard deviation of $5$ observations $x_1 ,x_2 ,x_3 ,x_4 ,x_5$ are $10$ and $3$, respectively, then the variance of $6$ observations $x_1 ,x_2 ,.....,x_3$ and $-50$ is equal to

  • [JEE MAIN 2019]
  • A

    $509.5$

  • B

    $586.5$

  • C

    $582.5$

  • D

    $507.5$

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