Statistics and Probability · StudentHub Lesson
Mean, Median and Mode
Calculate the mean, median and mode to describe the centre of a data set.
18 minBeginner
01
What you will learn
- Calculate the mean (average) of a data set
- Find the median by ordering data
- Identify the mode as the most frequent value
- Understand when each measure is most useful
- Compare data sets using these measures
02
Watch the lesson
Math Antics - Mean, Median and Mode · mathantics
Watch on YouTube03
Topic notes
Main Idea
Mean, median and mode are three ways to describe the 'average' or centre of a data set.
Key Concepts
- Mean is found by adding all values and dividing by the count
- Median is the middle value when data is ordered
- Mode is the value that appears most often
- Outliers affect the mean more than the median
Definitions
- Mean: sum of values divided by number of values
- Median: the middle number in an ordered data set
- Mode: the most frequently occurring value
Formulas
- Mean = (sum of all values) / (number of values)
- Median: order data; middle value (or average of the two middle values if the count is even)
Examples
- Data: 2, 4, 4, 6, 8 → Mean = 24/5 = 4.8, Median = 4, Mode = 4
- Data: 1, 3, 5, 7 → Median = (3+5)/2 = 4
Common Mistakes
- Forgetting to order data before finding the median
- Confusing mode (most frequent) with median (middle)
- Not dividing by the correct count for the mean
04
Key concepts
Mean calculationMedian calculationMode identificationEffect of outliersOrdering data sets
05
Important terms
- Mean
- The average, found by summing values and dividing by the count.
- Median
- The middle value of ordered data.
- Mode
- The most frequently occurring value.
06
Worked examples
Problem
Find the mean of 3, 7, 8, 10, 12
- 1. Sum values: 3+7+8+10+12=40
- 2. Divide by count: 40/5
Answer: 8
Problem
Find the median of 5, 3, 9, 1, 7
- 1. Order data: 1,3,5,7,9
- 2. Find the middle value
Answer: 5
07
Quick revision
- Mean = sum ÷ count
- Order data before finding the median
- Median with an even count: average the two middles
- Mode is the most repeated value
- A data set can have no mode or several
- Outliers skew the mean
08
Check your understanding
Question 1 · Multiple choice
What is the mean of 2, 4, 6, 8?
Question 2 · Multiple choice
What is the mode of 3, 5, 5, 7, 9?
Question 3 · Short answer
Find the median of 4, 1, 7, 3, 9.
Question 4 · Short answer
Find the mean of 10, 20, 30, 40.
Question 5 · True or false
A data set can have more than one mode.
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