The mean of $100$ items is $49$. It was discovered that three items which should have been $60, 70, 80$ were wrongly read as $40, 20, 50$ respectively. The correct mean is

The mean and the standard deviation of $10$ observations are $20$ and $2$ respectively. Each of these $10$ observations is multiplied by $p$ and then reduced by $q$,where $p \neq 0$ and $q \neq 0$. If the new mean and new standard deviation (s.d.) become half of the original values,then $q$ is equal to

The mean marks of $25$ boys in a class is $61$ and the mean marks of $35$ girls in the same class is $58$. Then,the mean of all $60$ students is (in $.25$)

Consider the statistics of two sets of observations as follows:

Set	Size	Mean	Variance
Observation $I$	$10$	$2$	$2$
Observation $II$	$n$	$3$	$1$

If the variance of the combined set of these two observations is $\frac{17}{9}$,then the value of $n$ is equal to:

An analysis of monthly wages paid to workers in two firms $A$ and $B$,belonging to the same industry,gives the following results:

\text{Parameter}	\text{Firm } $A$ \text{ and Firm } $B$
\text{No. of wage earners}	$A: 586, B: 648$
\text{Mean of monthly wages}	$Rs. 5253$
\text{Variance of wages}	$A: 100, B: 121$

Which firm,$A$ or $B$,pays a larger total amount as monthly wages?

If the coefficient of variation is $ 60 $ and the standard deviation is $ 24 $,then the arithmetic mean is: