Central Tendency & DispersionMTP Dec 22 - Series IQuestion 3188 of 473
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If the standard deviation of 1,2,3,4,...,10\displaystyle 1, 2, 3, 4, ..., 10 is σ\displaystyle \sigma, then the SD of 11,12,13,14,...,20\displaystyle 11, 12, 13, 14, ..., 20 is:

Options

A10σ\displaystyle 10\sigma
B10+σ\displaystyle 10+\sigma
Cσ\displaystyle \sigma
DNone of these
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Correct Answer

✅ Option c — σ\displaystyle \sigma

All Options:

  • A10σ\displaystyle 10\sigma
  • B10+σ\displaystyle 10+\sigma
  • Cσ\displaystyle \sigma
  • DNone of these

Detailed Solution & Explanation

**Key insight:** The series 11,12,13,...,20\displaystyle 11, 12, 13, ..., 20 is obtained by adding 10 to each term of 1,2,3,...,10\displaystyle 1, 2, 3, ..., 10. **Property:** Adding a constant to all observations does NOT change the Standard Deviation. **Proof:** If xi′=xi+10\displaystyle x_i' = x_i + 10, then xˉ′=xˉ+10\displaystyle \bar{x}' = \bar{x} + 10. xi′−xˉ′=(xi+10)−(xˉ+10)=xi−xˉx_i' - \bar{x}' = (x_i + 10) - (\bar{x} + 10) = x_i - \bar{x} Deviations are unchanged, hence SD is unchanged. **Conclusion:** SD of {11,12,...,20}\displaystyle \{11, 12, ..., 20\} = SD of {1,2,...,10}\displaystyle \{1, 2, ..., 10\} = σ\displaystyle \sigma Hence, **Option C** is the correct answer.

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