Solution:
Class | Frequency(y) | Class mark(x) | yx |
3-5 | 5 | 4 | 20 |
5-7 | 10 | 6 | 60 |
7-9 | 10 | 8 | 80 |
9-11 | 7 | 10 | 70 |
11-13 | 8 | 12 | 96 |
| ∑ y = 326 |
| ∑ yx = 326 |
Class mark of interval 3−5 and so on.
Step2:
We have the sigma of frequencies is 40 and sigma of yixi is 326 .
So, the mean of the given data is =
After solving means 326 divided by 40, we get
=
The mean value is 8.15