The mean of $10$ observations is $15.7$. If a new observation $19$ is included,the new mean is ..........

The formula to find the mean of an ungrouped data is ........

In the formula $\bar{x} = A + \frac{\Sigma f_{i} d_{i}}{\Sigma f_{i}}$ for the mean,$d_{i} = \dots$

For a given frequency distribution,$\Sigma f_{i} u_{i} = -13$,$n = \Sigma f_{i} = 100$,$A = 62.5$ and $c = 15$. Then,mean $\bar{x} = \dots$

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 $25$. Later on,it was found that one observation was taken by mistake as $20$ instead of $50$. Then,the correct mean is: