CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion
What is the standard deviation of the first seven natural numbers 1, 2, 3, 4, 5, 6, 7?
The standard deviation is 2. The mean is 4, the squared deviations sum to 28, so the variance is 4, and its square root is 2. The value 4 is only the variance.
- A2Correct
- B4
- C3
- D√7
Explanation
Mean = 4. Squared deviations are 9, 4, 1, 0, 1, 4, 9, summing to 28. Variance = 28/7 = 4, so SD = 2. The option 4 is the variance, not the SD. This agrees with the formula (n² − 1)/12 = 48/12 = 4.
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