Collect data and arrange them as shown in the table below. Find the sum of f and the sum of f*x.
| Data value (x) | Frequency (f) | Frequency*data value (fx). |
| 2 | 5 | 10 |
| 5 | 9 | 45 |
| 7 | 3 | 21 |
| 4 | 1 | 1 |
| Sum of f= 18. | Sum of f*x= 88. |
To get the mean, use the formulae: mean= sum of f*x /sum of f.
For the above case, mean=88/18
= 4.89.