Variance and Standard Deviation

Which of the following set of data has least standard deviation?

The variance of the variates $112,116,120,125,132$ about their A.M is

Let an angle of a triangle is $60°$. If the variance of the angles of the triangle is $4614°$, then the other two angles are

For a group of $100$ students, the mean ${\overline{x}}_1$ and the standard deviation ${\sigma }_1$ of their marks were found to be $40$ and $15$ respectively. Later it was observed that the scores $40$ and $50$ were misread as $30$ and $60$ respectively. If the mean and the standard deviation with the corrected observations of the scores are ${\overline{x}}_2$ and ${\sigma }_2$ respectively, then

The standard deviations of $x_i\left(i=1,2,\dots .10\right)$ and $y_i\left(i=1,\dots 10\right)$ are respectively $a$ and $b$. $\overline{x}, \overline{y}$ are the means of these two sets of observations respectively. If $z_i=\left(x_i-\overline{x}\right)\left(y_i-\overline{y}\right)$ and $\sum _{i=1}^{10}{z}_i=c$, then the standard deviation of the observations $\left(x_i-y_i\right), \left(i=1,2,\dots 10\right)$ is

The standard deviation of the numbers $22, 26, 28, 20, 24, 30$ is

The mean and variance of $n$ observations $x_1, x_2, x_3,\dots , x_n$ are $5$ and $0$ respectively. If $\sum _{i=1}^n{x}_i^2=400$, then the value of $n$ is equal to