Measures of Dis...

$5$ students of a class have an average height $150\ cm$ and variance $18\ cm^{2}$. A new student, whose height is $156\ cm$, joined them. The variance (in $cm^{2})$ of the height of these six students is

A student scores the following marks in five test: $45, 54, 41, 57, 43$. His score is not known for the sixth test. If the mean score is 48 in the six tests, then the standard deviation of the marks in six test is 

If the data $x_1, x_2, .., x_{10}$ is such that the mean of first four of these is $11$, the mean of the remaining six is $16$ and the sum of square of all of these is $2,000$; then the standard deviation of this data is?

For two data sets, each of size $5$, the variances are given to be $4$ and $5$  and the corresponding means are given to be $2$ and $4,$ respectively. The variance of the combined data set is 

The variance of first $50$ even natural numbers is

Find the Standard Deviation of of first $10$ multiples of $3$.

If the coefficient of variation and standard deviation of a distribution are 50% and 20 respectively, then its mean is

The variance of first n natural numbers is

Coefficient of deviation is calculated by the formula:

The mean deviation about median from the data
$340,150,210,240,300,310,320$ is