x | 5 | 10 | 15 | 20 | 25 |
f | 6 | 8 | 6 | y | 5 |
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 |
Class Interval | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 |
---|---|---|---|---|---|
Number of Students | 15 | 18 | 21 | 29 | 17 |
x | Less than 10 | Less than 20 | Less than 30 | Less than 40 | Less than 50 | Less than 60 |
f | 3 | 12 | 27 | 57 | 75 | 80 |
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