Average (Mean)
The central value of a set of numbers.
\text{Average} = \dfrac{\text{Sum of observations}}{\text{Number of observations}}
1What it means
The average (arithmetic mean) spreads the total equally across all items, giving a single representative value.
2Variables
| Symbol | Meaning |
|---|---|
| \text{Sum} | Total of all values |
| \text{Number} | How many values there are |
3Worked examples
Example 1 Worked solution
Q. Find the average of 10, 20, 30, 40.
- Sum = 10 + 20 + 30 + 40 = 100.
- Number of values = 4.
- Average = 100 / 4.
✓ Average = 25
4Where it's used
- ✦Average marks, speed, runs, temperature and income.
5Tips & common mistakes
- !Average always lies between the smallest and largest value.
- !For average speed over equal distances, use the harmonic mean, not this formula.