The word average mean middle or central point. Most of the time when we are required to calculate the average of a list of data we are supposed to calculate the ‘mean’ of the given data.
Formula to calculate average (mean) for ungrouped data.
Average is calculated by dividing the sum of the given data by the count of the same data.
Example:
A sample of 5 students was taken from an economics class to establish the average age of the class. The age of the students was listed as follows; 17yrs, 16yrs, 18yrs, 16yrs and 15yrs.Calculate the average age of the students.
Hence the average age of the students is 16.4 years.
Formula to calculate average ( mean ) for grouped data.
Here, we calculate mean by multiplying the summation of frequency and midpoint and then divide it by the total frequency.
Example:
| Class | Frequency (f) | Midpoint (m) | Product (m x f) |
| 1 – 5 | 4 | 3 | 12 |
| 6 – 10 | 7 | 8 | 56 |
| 11- 15 | 9 | 13 | 117 |
| Total | N = 20 | ( Σmf) = 185 |
