The mean and standard deviation of $10$ observations are $20$ and $84$ respectively. Later on, it was observed that one observation was recorded as $50$ instead of $40$. Then the correct variance is:

  • [JEE MAIN 2023]
  • A

    $14$

  • B

    $13$

  • C

    $12$

  • D

    $11$

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  • [IIT 2024]