If the means of the following frequency distribution is $18$, find the missing frequency.

Class of interval :	$11-13$	$13-15$	$15-17$	$17-19$	$19-21$	$21-23$	$23-25$
Frequency :	$3$	$6$	$9$	$13$	$f$	$5$	$4$

If the sum of the frequencies is $120$ and the mean is $50$ then find the sum of missing frequencies.

The daily income of a sample of $50$ employees are tabulated as follows:

Find the mean daily income of employees. 

The following is the distribution of height of students of a certain dass in a certain city:

Find the median height.

Following is the distribution of I.Q. of $100$ students. Find the median I.Q.

If the median salary of the following data giving salaries of $280$ persons is $₹\mathrm{S}$, then find the value of $\mathrm{S}$ (to the nearest whole number).

Calculate the median from the following data:

Calculate the missing frequency from the following distribution, it is given that the median of the distribution is $24$.