Question

Compute the median from the following data:
$\begin{array}{cccccccc}\text{Marks}& 0-7& 7-14& 14-21& 21-28& 28-35& 35-42& 42-49\\ \text{Numbers of}& & & & & & & \\ \text{students}& 3& 4& 7& 11& 0& 16& 9\end{array}$

Answer 1

We prepare the cumulative frequency table, as shown:

Marks	Number of students (f)	Cumulative frequency
0-7	3	3
7-14	4	7
14-21	7	14
21-28	11	25
28-35	0	25
35-42	16	41
42-49	9	50
	N=Σf=50

N= 50

⇒N/2=25

The cumulative frequency greater than 25 is 41 and the corresponding class is 35-42.

Thus the median class is 35-42.

Therefore, l=35, h = 7,
f = 16,
c.f. of preceding class = 25 and N/2=25

Median=l+((N/2−cf)/f)×h

Median=35+(25−25/16)×7

Median=35+0

Median=35