Q97 / 150 · MHT CET 2021 (24 Sep Shift 2) · Mathematics

For the set of 50 observation, the sum of their squares is 3050 , their arithmetic mean is 6 . Hence the standard deviation of these observations is

  • Correct answer
    A
    5
  • B
    3
  • C
    4
  • D
    6

Solution

We have $\mathrm{n}=50, \Sigma \mathrm{x}_{\mathrm{i}}^2=3050, \overline{\mathrm{x}}=6$ $\begin{aligned} & \text { S.D. }=\sqrt{\frac{1}{n} \Sigma x_i^2-(\bar{x})^2} \\ & =\sqrt{\frac{3050}{50}-(6)^2}=\sqrt{61-36}=\sqrt{25}=5 \end{aligned}$

Hence, the correct answer is option: 'A'.

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