Question

Find the median of the following data:

Class interval	$0-20$	$20-40$	$40-60$	$60-80$	$80-100$	$100-120$	$120-140$
Frequency	$6$	$8$	$10$	$12$	$6$	$5$	$3$

Answer 1

$ClassInterval$	$Frequency$	$c.f.$
$0-20$	$6$	$6$
$20-40$	$8$	$14$
$40-60$	$10$	$24$
$60-80$	$12$	$36$
$80-100$	$6$	$42$
$100-120$	$5$	$47$
$120-140$	$3$	$50$
	$N=50$

Here, $N=50$, then $\frac{N}{2}=\frac{50}{2}=25$

$\therefore$ Median class $=60-80$

We have, $l=60,c.f=24,f=12$ and $h=20$

$Median=l+\frac{\frac{N}{2}-c.f}{f}\times h$

$=60+\frac{25-24}{12}\times 20$

$=60+1.66$

$=61.66$