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 | 4 | 21 | 16 |
Here, the maximum class frequency is 23.
The class corresponding to this frequency is the modal class. ⇒ modal class = 12 - 15
Lets form a table.
CLASS | FREQUENCY(fi) | Cf |
3 - 6 | 7 | 7 |
6 - 9 | 13 | 7 + 13 = 20 |
9 - 12 | 10 | 20 + 10 = 30 |
12 - 15 | 23 | 30 + 23 = 53 |
15 - 18 | 4 | 53 + 4 = 57 |
18 - 21 | 21 | 57 + 21 = 78 |
21 - 24 | 16 | 78 + 16 = 94 |
TOTAL | 94 |
Since, modal class = 12 - 15, the corresponding cumulative frequency is 53.