If $1$ is added to each of the first $10$ natural numbers,then the variance of the numbers so obtained is:

Variance of first $n$ natural numbers is $\qquad$ .

If for a distribution $\Sigma(x-5)=3$,$\Sigma(x-5)^{2}=43$ and the total number of items is $18$,find the mean and standard deviation.

The sum and sum of squares corresponding to length $x$ (in $cm$) and weight $y$ (in $gm$) of $50$ plant products are given below:
$\sum\limits_{i = 1}^{50} {{x_i} = 212, \sum\limits_{i = 1}^{50} {x_i^2} = 902.8, \sum\limits_{i = 1}^{50} {{y_i} = 261, \sum\limits_{i = 1}^{50} {y_i^2 = 1457.6} } }$
Which is more varying,the length or weight?

If the total number of observations is $n = 20$,$\sum x_i = 1000$ and $\sum x_i^2 = 84000$,then the variance of the distribution is

The variance of the following distribution is:

Marks	$1-3$	$3-5$	$5-7$	$7-9$
Number of students	$40$	$30$	$20$	$10$