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11+ Maths Guide · Year 5–6 · Free lesson

Ratio Problem Solving

The 11+'s hardest ratio questions hide the total and hand you a share or a difference instead. The fix never changes: work out what the number represents, drop to one part, scale up. This final lesson drills exactly that.

R10Ratio Problem Solving
Ratio puzzles, exam style.
The hardest ratio questions give a part or a difference, not the total — work back to one part.
Mia and Sam share money 3 : 2. Sam gets £8. How much was shared?
Sam's 2 parts = £8 → 1 part = £4
5 parts = 5 × £4 = £20
Whatever you're given — total, one share, or the difference — turn it into ONE PART first.
1

Learn the 3-Step Method

1Identify what the number IS.

£8 isn't the total — it's Sam's share, which is 2 parts.

£8 = 2 parts

2Drop to one part.

2 parts = £8 → 1 part = £4.

1 part = £4

3Scale to what's asked.

Total 5 parts = £20; Mia's 3 parts = £12; difference = £4.

×5, ×3, ×1
💡 Key Idea‘One part’ is the master key: every ratio puzzle, whatever it gives you, is solved by finding one part first.
2

Worked Example

Tom and Jo share stickers 5 : 3. Tom has 12 MORE than Jo. How many do they have altogether?

The difference in parts
5 − 3 = 2 parts = 12
One part
12 ÷ 2 = 6
✓ Total
8 × 6 = 48
48 stickers
Tom 30, Jo 18; 30 − 18 = 12 ✓
3

Watch Out! Common Mistakes

Treating the given number as the total.
£8 shared 3:2 → £4.80 and £3.20 ✕

Read again! £8 was SAM’S share (2 parts), so one part is £4 and the total is £20.

Difference over the wrong parts.
12 more, ratio 5:3 → 12 ÷ 8 = 1.5 ✕

The difference is 2 parts! (5 − 3). 12 ÷ 2 = 6 per part → total 48.

Not verifying with the story.

Rebuild it! Tom 30, Jo 18: ratio 30:18 = 5:3 ✓, difference 12 ✓. If either fails, restart from ‘what does the number represent?’.

Cheat Sheet

RATIO PROBLEM SOLVING
  1. Ask: is the given number the total, one share, or the difference?
  2. Convert it to parts, then find ONE part.
  3. Scale to whatever is asked.
  4. Rebuild the story to check both facts.
Examples: Sam(2 parts)=£8 → total £20 · diff(2 parts)=12 → total 48.
📄 Free printable: Download the Ratio Problem Solving cheat sheet (PDF) — keep it by your child's desk.

Quick summary

Frequently asked questions

How do you solve a ratio problem when you're given one share?

Match the share to its parts: if Sam's 2 parts are £8, one part is £4, so the 5-part total is £20.

How do you use a difference in a ratio problem?

The difference corresponds to the difference in parts: sharing 5 : 3 with 12 more for the first person means 2 parts = 12, one part = 6, total 48.

What single habit solves every ratio puzzle?

Finding the value of one part first — every given (total, share or difference) converts to it, and every answer scales from it.

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