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NDA 2 2025 Maths, question 115

Topic: Statistics

Q115

The standard deviation of 100100 observations is 1010. If 2020 is added to each observation, then what will be the new standard deviation?

  1. (a) 1010Correct answer
  2. (b) 1515
  3. (c) 2020
  4. (d) 2525

Solution.

Answer: (a) 1010

  1. Adding 20 shifts both every observation and the mean by 20.
  2. Each deviation from the mean is unchanged, so variance and standard deviation remain unchanged.
  3. The new standard deviation is 10.