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Updated Mar 18, 2026

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2 pages

Understanding Histograms and Frequency Tables

Kate Robinson

@katerobinson_rafs

Statistical graphs and frequency analysis are essential tools for understanding... Show more

# Histograms

Bar chart
height of
bar tells us
frequency
DISCRETE
DATA

Histo eran
(area of
bor tells us
frequency
CONTINUOUS
DATA
Gerlange

Histograms vs Bar Charts

Ever wondered why some graphs look similar but work completely differently? Bar charts use the height of bars to show frequency and work with discrete data (like shoe sizes or favourite colours). Histograms are trickier - they use the area of bars to show frequency and handle continuous data (like heights or times).

The key formula you absolutely must remember is: Frequency = Frequency density × Class width. This means the height of each bar (frequency density) multiplied by its width gives you the actual frequency. It's like calculating the area of a rectangle!

When drawing histograms, accuracy matters loads. Use a ruler, label your axes clearly, and remember there are no gaps between bars (unlike bar charts). Don't rush your frequency density calculations - show your working step by step.

Top Tip: Always double-check your frequency density calculations before drawing. One small error can mess up your entire histogram!

Frequency Tables and Analysis

Frequency tables might look boring, but they're actually data goldmines that help you find patterns and answer exam questions worth serious marks. The cumulative frequency column shows running totals - just add each frequency to the previous total.

To find the estimated mean, use the formula: Sum of (midpoint × frequency) ÷ total frequency. Pick the midpoint of each class interval, multiply by its frequency, add them all up, then divide by the total number of values.

The modal class is simply the group with the highest frequency - easy marks if you spot it quickly! For the median, find the middle position (total ÷ 2) and see which class it falls into using your cumulative frequency.

Exam Smart: Cumulative frequency graphs use smooth curves, not straight lines. Connect your plotted points with a flowing curve to find the median accurately.

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346

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Updated Mar 18, 2026

•

2 pages

Understanding Histograms and Frequency Tables

Kate Robinson

@katerobinson_rafs

Statistical graphs and frequency analysis are essential tools for understanding data patterns in maths. You'll encounter histograms and frequency tables in your GCSE exams, so mastering these concepts now will boost your confidence and marks.

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Histograms vs Bar Charts

Top Tip: Always double-check your frequency density calculations before drawing. One small error can mess up your entire histogram!

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Frequency Tables and Analysis

Exam Smart: Cumulative frequency graphs use smooth curves, not straight lines. Connect your plotted points with a flowing curve to find the median accurately.