Question

What is the cumulative frequency of the modal class of the following distribution?

Class	3 – 6	6 – 9	9 – 12	12 – 15	15 – 18	18 – 21	21 – 24
Frequency	7	13	10	23	54	21	16

Answer 1

Here the maximum class frequency is 23, and the class corresponding to this frequency is 12-15.

So, the modal class is 12.15.
Now, to find the cumulative frequency let us put the data in the table given below:

Class	Frequency` (f_i)`	Cumulative frequency (𝑐𝑓)
3-6	7	7
6-9	13	20
9-12	10	30
12-15	23	53
15-18	4	5
18-21	21	78
21-24	16	94
Total	`N= Σf_i=94`

Thus, the cumulative frequency of the modal class is 53.