STA010 · Probability & statistics · Classes 8–10
Frequency tables
A frequency table groups data into classes and counts how many values fall in each. The class with the highest frequency is the modal class.
tallyFrequency tables
📐 Formula
frequency = count in each class; Σ f = n
✏️ Worked example
20 test marks in classes of width 20: 0–19: 1, 20–39: 2, 40–59: 6, 60–79: 7, 80–99: 4. Modal class 60–79.
🌍 Where it is used
Summarising survey and exam results.
❓ Quick check
Sum of all frequencies equals…
🏋️ Practice
EasyHow many marks lie between 40 and 59?
Answer: 6
MediumClasses of width 10 from 0 to 99: how many?
Answer: 10
ChallengeWhat is the modal class with width 20?
Answer: 60–79