The variance of first 50 even natural numbers is

The variance of first 50 even natural numbers is
  1. 833
  2. 473
  3. $\frac{437}{4}$
  4. $\frac{833}{4}$

Solution

$\begin{aligned} & \text { Variance }=\frac{\sum x_{\mathrm{i}}^2}{\mathrm{n}}-(\bar{x})^2 \\ & =\frac{\left(2^2+4^2+\ldots+100^2\right)}{50}-\left(\frac{2+4+\ldots+100}{50}\right)^2 \\ & =\frac{4\left(1^2+2^2+\ldots .+50^2\right)}{50}-(51)^2 \\ & =4\left(\frac{50 \times 51 \times 101}{50 \times 6}\right)-(51)^2 \\ & =3434-2601 \\ & =833\end{aligned}$

Asked in: MHT CET 2024 (04 May Shift 1)

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