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NDA 2023 Maths · Mathematics · Statistics · medium

The standard deviation of the data 2,4,4,4,5,5,7,9 is

Single correct option

The standard deviation of the data 2,4,4,4,5,5,7,92,4,4,4,5,5,7,9 is
  1. A. 22
  2. B. 44
  3. C. 5\sqrt5
  4. D. 33
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Answer: (A) 22

The mean is 55. The squared deviations are 9,1,1,1,0,0,4,169,1,1,1,0,0,4,16 with sum 3232, so the variance is 328=4\dfrac{32}{8}=4 and the standard deviation is 22. The value 44 is the variance.
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Original question written in the NDA 2023 Maths pattern and checked twice for the correct answer. Not an official question paper. How we write and check questions · Corrections policy · Report a mistake