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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 |
Solution
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.
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