For a given frequency distribution,$A = 200$,$\Sigma f_{i} = 45$,$\Sigma f_{i} u_{i} = -216$ and $c = 10$. Then,mean $\bar{x} = \dots$

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	$2$	$4$	$7$	$6$	$1$

The mileage $(km/l)$ of $50$ cars of the same model was tested by a manufacturer and details are tabulated as given below:

Mileage $(km/l)$	$10-12$	$12-14$	$14-16$	$16-18$
Number of cars	$7$	$12$	$18$	$13$

Find the mean mileage.
The manufacturer claimed that the mileage of the model was $16 \, km/l$. Do you agree with this claim?

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

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.

Calculate the mean of the frequency distribution of the marks scored by $100$ students in a mathematics test:

Marks	$0-10$	$10-20$	$20-30$	$30-40$	$40-50$
No. of students	$20$	$10$	$20$	$30$	$20$