2. Draw Ogive (cumulative frequency curve)
| Class | Frequency |
| 10 - 20 | 15 |
| 20 - 30 | 25 |
| 30 - 40 | 20 |
| 40 - 50 | 12 |
| 50 - 60 | 8 |
| 60 - 70 | 5 |
| 70 - 80 | 3 |
Solution:
To draw Less than type cumulative frequency curve, we first prepare the following table
| Class | Frequency
`f` | < Upper | `cf` |
| 0 - 10 | - | 10 | 0 |
| 10 - 20 | 15 | 20 | 0 + 15 = 15 |
| 20 - 30 | 25 | 30 | 15 + 25 = 40 |
| 30 - 40 | 20 | 40 | 40 + 20 = 60 |
| 40 - 50 | 12 | 50 | 60 + 12 = 72 |
| 50 - 60 | 8 | 60 | 72 + 8 = 80 |
| 60 - 70 | 5 | 70 | 80 + 5 = 85 |
| 70 - 80 | 3 | 80 | 85 + 3 = 88 |
To draw More than type cumulative frequency curve, we first prepare the following table
Total frequency = 88
| Class | Frequency
`f` | > Lower | `cf` |
| 10 - 20 | 15 | 10 | 88 |
| 20 - 30 | 25 | 20 | 88 - 15 = 73 |
| 30 - 40 | 20 | 30 | 73 - 25 = 48 |
| 40 - 50 | 12 | 40 | 48 - 20 = 28 |
| 50 - 60 | 8 | 50 | 28 - 12 = 16 |
| 60 - 70 | 5 | 60 | 16 - 8 = 8 |
| 70 - 80 | 3 | 70 | 8 - 5 = 3 |
| 80 - 90 | - | 80 | 3 - 3 = 0 |
This material is intended as a summary. Use your textbook for detail explanation.
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