For a given frequency distribution,$n=100$ and $\Sigma f_{i} x_{i}=245$. Then,$\bar{x}=\ldots \ldots \ldots \ldots$

For a given frequency distribution,$\bar{x} = 19.7$,$A = 20$,and $n = 50$. Then,$\Sigma f_{i} d_{i} = \ldots$

Consider the following distribution of daily wages of $50$ workers of a factory.
$\begin{array}{|l|c|c|c|c|c|} \hline \text{Daily wages (in Rs.)} & 100-120 & 120-140 & 140-160 & 160-180 & 180-200 \\ \hline \text{Number of workers} & 12 & 14 & 8 & 6 & 10 \\ \hline \end{array}$
Find the mean daily wages of the workers of the factory by using an appropriate method.

The mean of $15$ observations is $16$. If $2$ is added to each observation and then each result is divided by $3$,the new mean is:

Calculate the mean of the scores of $20$ students in a mathematics test:

Marks	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$
Number of students	$2$	$4$	$7$	$6$	$1$

For a given frequency distribution,$\Sigma f_{i} d_{i} = -50$,$\Sigma f_{i} = 200$ and $A = 62.5$. Then the mean $\bar{x} = $ ........