1. Draw Ogive (cumulative frequency curve)
| Class | Frequency |
| 20 - 25 | 110 |
| 25 - 30 | 170 |
| 30 - 35 | 80 |
| 35 - 40 | 45 |
| 40 - 45 | 40 |
| 45 - 50 | 35 |
Solution:
To draw Less than type cumulative frequency curve, we first prepare the following table
| Class | Frequency
`f` | < Upper | `cf` |
| 15 - 20 | - | 20 | 0 |
| 20 - 25 | 110 | 25 | 0 + 110 = 110 |
| 25 - 30 | 170 | 30 | 110 + 170 = 280 |
| 30 - 35 | 80 | 35 | 280 + 80 = 360 |
| 35 - 40 | 45 | 40 | 360 + 45 = 405 |
| 40 - 45 | 40 | 45 | 405 + 40 = 445 |
| 45 - 50 | 35 | 50 | 445 + 35 = 480 |
To draw More than type cumulative frequency curve, we first prepare the following table
Total frequency = 480
| Class | Frequency
`f` | > Lower | `cf` |
| 20 - 25 | 110 | 20 | 480 |
| 25 - 30 | 170 | 25 | 480 - 110 = 370 |
| 30 - 35 | 80 | 30 | 370 - 170 = 200 |
| 35 - 40 | 45 | 35 | 200 - 80 = 120 |
| 40 - 45 | 40 | 40 | 120 - 45 = 75 |
| 45 - 50 | 35 | 45 | 75 - 40 = 35 |
| 50 - 55 | - | 50 | 35 - 35 = 0 |
This material is intended as a summary. Use your textbook for detail explanation.
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