Question

Write the median class of the following distribution: [CBSE 2009]

Class	0−10	10−20	20−30	30−40	40−50	50−60	60−70
Frequency	4	4	8	10	12	8	4

Answer 1

To find the median let us put the data in the table given below:

Class	Frequency (fi)	Cumulative frequency (cf)
0−10	4	4
10−20	4	8
20−30	8	16
30−40	10	26
40−50	12	38
50−60	8	46
60−70	4	50
Total	N = ∑fi = 50

Now, N = 50 $\Rightarrow \frac{N}{2}=25$.

The cumulative frequency just greater than 25 is 26, and the corresponding class is 30−40.

Thus, the median class is 30−40.