If the mean and variance of five observations are $\frac{24}{5}$ and $\frac{194}{25}$ respectively and the mean of first four observations is $\frac{7}{2}$, then the variance of the first four observations in equal to
$\frac{4}{5}$
$\frac{77}{12}$
$\frac{5}{4}$
$\frac{105}{4}$
The mean and variance of eight observations are $9$ and $9.25,$ respectively. If six of the observations are $6,7,10,12,12$ and $13,$ find the remaining two observations.
The mean and $S.D.$ of $1, 2, 3, 4, 5, 6$ is
If the variance of the first $n$ natural numbers is $10$ and the variance of the first m even natural numbers is $16$, then $m + n$ is equal to
The number of values of $a \in N$ such that the variance of $3,7,12 a, 43-a$ is a natural number is (Mean $=13$)
If the variance of the following frequency distribution is $50$ then $x$ is equal to:
Class | $10-20$ | $20-30$ | $30-40$ |
Frequency | $2$ | $x$ | $2$ |