Calculate the mean as an average by adding values and dividing by the count
The mean (also called the average) is a way to find a typical or representative value for a set of numbers. To calculate it, you add up all the values and divide by how many values there are. The mean is one of the most commonly used measures in statistics because it uses all the data and provides a single number that represents the whole set.
The mean gives a single value that represents an entire data set, making it easy to understand and communicate.
Used everywhere to compare groups, track progress, and make informed decisions based on data.
From test scores to sports statistics to weather data, means are used daily in almost every field.
Sarah scored 78, 82, 85, 88, and 92 on her five maths tests. What is her mean score?
Step 1: Add all scores
78 + 82 + 85 + 88 + 92 = 425
Step 2: Count the tests = 5
Step 3: Divide sum by count
425 ÷ 5 = 85
Answer: Mean score is 85
The daily temperatures for a week were: 18°C, 20°C, 19°C, 22°C, 21°C, 23°C, 19°C. Find the mean.
Step 1: Add all temperatures
18 + 20 + 19 + 22 + 21 + 23 + 19 = 142
Step 2: Count the days = 7
Step 3: Divide sum by count
142 ÷ 7 = 20.29°C (rounded to 2 dp)
Answer: Mean temperature is approximately 20°C
Five pupils have heights: 142cm, 138cm, 145cm, 140cm, 135cm. Calculate the mean height.
Step 1: Add all heights
142 + 138 + 145 + 140 + 135 = 700
Step 2: Count the pupils = 5
Step 3: Divide sum by count
700 ÷ 5 = 140
Answer: Mean height is 140cm
A football team scored 3, 2, 4, 1, 5, 2, 3 goals in their last 7 matches. What is their mean?
Step 1: Add all goals
3 + 2 + 4 + 1 + 5 + 2 + 3 = 20
Step 2: Count the matches = 7
Step 3: Divide sum by count
20 ÷ 7 = 2.86 (rounded to 2 dp)
Answer: Mean goals per match ≈ 2.9
Learn from typical errors students make and discover how to avoid them!
What students often do wrong:
Students forget to count all values or miscount them, leading to dividing by the wrong number. This is especially common when values repeat or when the data set is long.
Correct approach: Count each value carefully, even if the same number appears multiple times. Each occurrence counts separately!
Memory tip: "Every value counts, don't leave any out" - count systematically from left to right.
What students often do wrong:
Students confuse the mean with the median (middle value) and simply pick the middle number instead of calculating the average.
Correct approach: Always add ALL values together first, then divide by the count. Don't take shortcuts!
Memory tip: "Mean needs sum and divide, not just picking from the side!"
Check your answer makes sense! The mean should always be between the smallest and largest values in your data set. If your calculated mean is outside this range, check your arithmetic. Also, the mean might not be one of the actual values in the set - that's perfectly normal!
You've mastered Calculating the Mean Average!
Next: Learn to interpret and use the mean in real-world problem-solving contexts