Understanding the Mean
The arithmetic mean is one of the most commonly used measures of central tendency. It gives us a single value that represents the average of a collection of numbers.
Teaching idea: Imagine five students scored 60, 70, 75, 85 and 90 marks. What single number could help describe their overall performance?
The mean is calculated by adding all observations and dividing the sum by the total number of observations.
Mean = (Sum of all observations) / (Number of observations)
Worked example
Scores: 60, 70, 75, 85, 90
Step 1: Add the scores → 60 + 70 + 75 + 85 + 90 = 380
Step 2: Count the scores → 5 observations
Step 3: Divide → 380 ÷ 5 = 76
Remember: The mean uses every value in the dataset, so unusually high or low values can affect it.
Check your understanding
Find the mean of 4, 6, 8 and 10. First calculate the sum, then divide by the number of values.
Demo content only. Upload your own PDF to render its pages here. Select any text and use the right panel to enlarge and explain it.