The masses in kg of $60$ boys of a certain age were found to give the following distribution:

Mass	$35-40$	$40-45$	$45-50$	$50-55$	$55-60$	$60-65$	$65-70$	$70-75$
Number of boys	$3$	$7$	$$$10$	$17$	$13$	$6$	$3$	$1$

Estimate the mean mass.

The following table gives the lifetime in days of $100$ electricity tubes of a certain make:

For the following frequency distribution, find the mean daily wage of a worker of a factory:

The following table gives the daily wages of $50$ workers of a factory:

Calculate the average daily wages.

The following table gives the daily wages of $50$ workers of a factory:

If daily wages of all workers are increased by $₹8$, what will be the new average daily wage?

The following table gives the daily wages of $50$ workers of a factory:

If, instead, the daily wages of all workers are increased by $20\%$, what will be the new average daily wage?

A trader takes a sample of $50$ eggs and weights them. The following table gives his findings:

Calculate the mean weight to the nearest $g$.

A trader takes a sample of $50$ eggs and weights them. The following table gives his findings:

If $10$ eggs each weighing $100$ g are added, what is the new mean weight? Calculate by using formula combined mean.

The mean of the following distribution is $52.$ Determine the value of $f:$