This exam tips covers Common Mistakes to Avoid within Ratio Basics for GCSE Mathematics. Revise Ratio Basics in Number for GCSE Mathematics with 12 exam-style questions and 22 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 13 of 15 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Common Mistakes to Avoid
❌ Wrong: Adding to ratios: 2:3 + 1:2 = 3:5
✅ Right: Cannot add ratios directly
Convert to fractions or find common format first
❌ Wrong: Ignoring order: 3:5 same as 5:3
✅ Right: Order matters in ratios
3:5 means first is 3 parts, second is 5 parts
❌ Wrong: Not converting units: 2m : 50cm = 2:50
✅ Right: 200cm : 50cm = 4:1
Always convert to same units before simplifying
❌ Wrong: Forgetting to simplify: Answer 10:15
✅ Right: 10:15 = 2:3
Always give ratio in simplest form
Practice questions for Ratio Basics
Write the ratio 12:18 in its simplest form.
Explain the difference between the ratio 3:5 and the ratio 5:3.
Quick recall flashcards
Order in Ratios
Order MATTERS!
Boys:Girls = 3:5 means:
• 3 boys for every 5 girls
Girls:Boys = 5:3 means:
• 5 girls for every 3 boys
Different meanings!
What is a ratio?
A comparison of quantities of the same kind
Written as a:b or a/b
Example: 3:5 means '3 parts to 5 parts'