Find the median for the following distribution:

Class	Frequency
$10-20$	$180$
$20-30$	$82$
$30-40$	$34$
$40-50$	$180$
$50-60$	$136$
$60-70$	$23$
$70-80$	$50$

The mean of a set of observations is $\bar{x}$. If each observation is divided by $\alpha$ $(\alpha \neq 0)$ and then increased by $10$,what is the mean of the new set?

The arithmetic mean of $n$ observations is $\bar{x}$. If the sum of $n - 4$ observations is $K$,what is the mean of the remaining observations?

The geometric mean of the numbers $4, 5, 10, 20, 25$ is .........

Find the median of the sequence $^{2n}C_0, ^{2n}C_1, ^{2n}C_2, \dots, ^{2n}C_n$ (where $n$ is even).

In a class of $100$ students,there are $70$ boys whose average marks in a subject are $75$. If the average marks of the complete class are $72$,then what are the average marks of the girls?