What is important to know about Frequency polygons?

Plot the midpoint of each class on the x-axis.

What is important to know about Frequency polygons?

Plot the frequency on the y-axis.

What is important to know about Frequency polygons?

Join the points with straight line segments.

📊

Statistics & Probability · Foundation & Higher

Frequency polygons

A frequency polygon is a line graph showing frequencies of grouped data. Plot the frequency against the midpoint of each class interval and join the points with straight lines.

Put your revision into practice

Choose a topic and try a short quiz with instant explanations. Free, with no signup.

Choose a free quiz Find a worked example

Revising frequency polygons the night before an exam? These are condensed revision notes — the facts, formulas and mistakes examiners actually mark, with no long explanations. Prefer a full walkthrough with step-by-step reasoning instead? Search “Frequency polygons GCSE” on the site for the complete guide.

🔑

Key facts to remember

1Plot the midpoint of each class on the x-axis.
2Plot the frequency on the y-axis.
3Join the points with straight line segments.
4Do NOT join to the x-axis at either end.
5Used for comparing two distributions on the same axes.

✍️

Worked examples

Example 1

Draw a frequency polygon for: 0–10 → 4; 10–20 → 9; 20–30 → 15; 30–40 → 7.

Working

Midpoints: 5, 15, 25, 35.
Plot (5, 4), (15, 9), (25, 15), (35, 7).
Join with straight line segments.

AnswerA polygon peaking at midpoint 25 with frequency 15.

⚠️

Common mistakes

✗Plotting at the class boundary instead of the midpoint.

✗Joining the first or last point down to the x-axis.

✗Confusing a frequency polygon with a histogram.

🎯

Exam tips

✓Always use the midpoint of the interval, not the upper/lower bound.

✓Label both axes clearly.

✓When comparing two sets, draw both polygons on the same axes with a key.

Ready to test yourself on Frequency polygons?

Get AI-marked practice questions on exactly this subtopic.

Practice this topic →

← All topics Dashboard

▶️ Watch on YouTube

Free video lessons

Click a topic to search

▶frequency polygons GCSE ▶drawing frequency polygons GCSE maths ▶frequency polygon interpretation GCSE

Opens YouTube — pick any free GCSE video.