The mean and standard deviation of $100$ observations were calculated as $40$ and $5.1$,respectively,by a student who took by mistake $50$ instead of $40$ for one observation. What are the correct mean and standard deviation?

  • A
    $39.9, 5$
  • B
    $40, 5.1$
  • C
    $39.9, 4.9$
  • D
    $40, 4.9$

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