What is Mean, Median and Mode?
Mean, median and mode are the three main ways to describe the 'center' of a data set. The mean is the sum of values divided by count, the median is the middle value of sorted data, and the mode is the most frequent value.
The mean (x̄ = Σx/n) is the average of all values; the median is the middle value of sorted data; the mode is the value that appears most often.
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Step-by-step worked examples
Find the mean of these test scores: 70, 80, 90, 60, 100.
Sum = 70+80+90+60+100 = 400 Mean = 400/5 = 80
Find the median of the data set: 12, 4, 9, 7, 15.
Sort: 4, 7, 9, 12, 15 Middle value (3rd of 5) = 9
Find the mode of the data set: 2, 3, 3, 5, 7, 3, 8.
Count frequencies: 2→1, 3→3, 5→1, 7→1, 8→1 Most frequent value = 3 → mode = 3
Flashcards
Quick quiz
Q1.What is the mean of 5, 10, 15, 20, 25?
Q2.What is the median of 3, 1, 4, 1, 5?
Q3.Which measure of central tendency can a data set have more than one of?
Q4.Which measure works best for skewed data with outliers?
The full card deck, worked steps and AI-tutor support for “What is Mean, Median and Mode?” are in Notek — study by hand before your exam.
Common mistakes
Finding the median without sorting the data first. — Correct: Sort the data first — the median is the middle value of ordered data.
Assuming a data set can only have one mode. — Correct: A data set can have no mode, one mode, or several modes (bimodal/multimodal).
Assuming the mean is always the best measure of center. — Correct: For skewed data or outliers, the median usually represents the data better.
Picking one of the two middle numbers as the median for an even count. — Correct: For an even count, median = average of the two middle numbers.
FAQ
What is mean, median and mode?
The mean is the average of all values, the median is the middle value of sorted data, and the mode is the most frequent value.
What is the formula for mean, median and mode?
Mean: x̄ = Σx/n. Median: the middle value of sorted data. Mode: the most frequently occurring value (no formula, just counting).
What are examples of mean, median and mode?
Scores 70,80,90,60,100 have a mean of 80; data 4,7,9,12,15 has a median of 9; data 2,3,3,5,7,3,8 has a mode of 3.
How do you calculate mean, median and mode?
For mean, sum the values and divide by count. For median, sort the data and take the middle value. For mode, find the value that repeats most.