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Find the standard deviation of the first ‘n’ natural numbers.
Question

Find the standard deviation of the first ‘n’ natural numbers.

A.

n2112\sqrt{\frac{n^2 -1}{12}}​​

B.

n(2n+1)3\frac{n(2n+1)}{3}​​

C.

n(n+1)12\frac{n(n+1)}{12}​​

D.

n2+16\sqrt{\frac{n^2+1}{6}}​​

Correct option is A

Given
​The first n natural numbers are 1, 2, 3,……,n.
Formula Used
Mean (μ) of the first n natural numbers:
μ=Sum of first n natural numbersn=n(n+1)2n=n+12\mu = \frac{\text{Sum of first } n \text{ natural numbers}}{n} = \frac{n(n+1)}{2n} = \frac{n+1}{2}​​
Variance (σ2\sigma^2) of the first n natural numbers:
σ2=Sum of squares of first n natural numbersnμ2\sigma^2 = \frac{\text{Sum of squares of first } n \text{ natural numbers}}{n} - \mu^2​​
Sum of squares=n(n+1)(2n+1)6\text{Sum of squares} = \frac{n(n+1)(2n+1)}{6}​​
Standard deviation (σ): σ=σ2\sigma = \sqrt{\sigma^2}​​
Solution

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