Find the median of the following frequency distribution:

Class	$0-20$	$20-40$	$40-60$	$60-80$	$80-100$
Frequency	$5$	$15$	$20$	$18$	$2$

The median class of the following frequency distribution is ...........

Class	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$	$70-80$
Frequency	$6$	$10$	$5$	$6$	$4$	$2$	$2$

In the formula $M = l + \frac{(\frac{n}{2} - cf)}{f} \times h$ for the median,$n = \ldots \ldots \ldots$

While computing the mean of grouped data,we assume that the frequencies are

The following are the ages of $300$ patients getting medical treatment in a hospital on a particular day:

Age (in years)	$10-20$	$20-30$	$30-40$	$40-50$	$50-60$	$60-70$
Number of patients	$60$	$42$	$55$	$70$	$53$	$20$

Form:
$(i)$ Less than type cumulative frequency distribution.
$(ii)$ More than type cumulative frequency distribution.

For the following distribution:

Class	$0-5$	$5-10$	$10-15$	$15-20$	$20-25$
Frequency	$10$	$15$	$12$	$20$	$9$

the sum of the lower limits of the median class and the modal class is: