Histograms

Key idea

Bars showing frequency of numerical intervals.

In depth

A histogram groups numerical data into intervals (bins), with bars touching to show a continuous scale. The area of each bar represents frequency, so equal-width bins are easiest to read. It reveals shape: symmetric, skewed or bimodal.

Worked example

Exam scores in bins 0–10, 10–20, and so on reveal a peak around 60–70.

Real-world uses

• Showing the spread of exam marks, heights or waiting times in a report

Common mistake

Confusing it with a bar graph and leaving gaps or using uneven bins without adjusting heights.

How to learn this

1. Read the key idea and say it in your own words.
2. Work through the worked example, then try a similar problem.
3. Use the interactive lesson’s visual and mini-quiz to check the pattern.

Frequently asked questions

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Related intermediate topics in Probability & Statistics

• Collecting Data and Sampling – Surveys, experiments and random sampling.
• Bias in Sampling – Systematic errors that make samples unrepresentative.
• Dot Plots and Stem-and-Leaf Plots – Show the shape of small datasets.
• Mean – The arithmetic average.
• Median – The middle value of an ordered list.
• Range – Difference between maximum and minimum.