| Number of students per Teacher | Number of Schools |
| 20 - 25 | 5 |
| 25 - 30 | 15 |
| 30 - 35 | 25 |
| 35 - 40 | 30 |
| 40 - 45 | 15 |
| 45 - 50 | 10 |
| Number of students per Teacher | Number of Schools |
| 20 - 25 | 5 |
| 25 - 30 | 15 |
| 30 - 35 | 25 |
| 35 - 40 | 30 |
| 40 - 45 | 15 |
| 45 - 50 | 10 |
If the variance of the frequency distribution
| xi | Frequency ft |
| 2 | 3 |
| 3 | 6 |
| 4 | 16 |
| 5 | \(\alpha\) |
| 6 | 9 |
| 7 | 5 |
| 8 | 6 |
is 3 , then $\alpha$ is equal to