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CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion

What is the variance of the first 11 natural numbers, 1, 2, 3, …, 11?

The variance is 10. For the first n natural numbers the variance is (n² − 1)/12. With n = 11 this is 120/12 = 10. Using n²/12 gives about 10.08, and 11 and 12 have no basis in the formula.

  1. A10Correct
  2. B11
  3. C10.08
  4. D12

Explanation

For the first n natural numbers, variance = (n²−1)/12. With n = 11, this is (121−1)/12 = 120/12 = 10. The value 10.08 comes from wrongly using n²/12.

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