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NDA 1 2025 Maths, question 114

Topic: Statistics

Q114

The standard deviation of 100 observations is 10. If 5 is added to each observation and then divided by 20, then what will be the new standard deviation?

  1. (a) 0.25
  2. (b) 0.5Correct answer
  3. (c) 0.75
  4. (d) 1.00

Solution.

Answer: (b) 0.5

  1. Adding a constant does not alter spread.
  2. Dividing all observations by 20 divides their standard deviation by 20.
  3. Hence the new standard deviation is 10/20=0.510/20 = 0.5.