The mean and variance of a series of $5$ observations are $8$ and $24$ respectively. The mean and variance of another series of $3$ observations are $8$ and $24$ respectively. What is the variance of their combined series?

If variables $x$ and $u$ are related by $u = \frac{x - a}{h}$,then the correct relationship between $\sigma_x$ and $\sigma_u$ is:

The marks obtained by students $A$ and $B$ in $3$ examinations are given below:
| | Exam $1$ | Exam $2$ | Exam $3$ |
|---|---|---|---|
| Marks of $A$ | $30$ | $20$ | $40$ |
| Marks of $B$ | $70$ | $0$ | $5$ |
The ratio of the coefficient of variation of marks of $A$ and the coefficient of variation of marks of $B$ is:

If the coefficient of variation and variance of a frequency distribution are $7.2$ and $3.24$ respectively,then its mean is

In a series of $2n$ observations,half of them are equal to $a$ and the remaining half are equal to $-a$. If the standard deviation of these observations is $2$,then $|a|$ equals:

Let $X = \{x \in N : 1 \leq x \leq 17\}$ and $Y = \{ax + b : x \in X \text{ and } a, b \in R, a > 0\}$. If the mean and variance of the elements of $Y$ are $17$ and $216$ respectively,then $a + b$ is equal to: