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Improve Tuition · Foundation Maths · Year 6–10
Number · Ratio & Proportion

Ratio & Proportion

Comparing amounts, sharing fairly, and scaling up and down.

5 lessons · 35 questions (A–G) · 20 calculation + 15 word problems · no time pressure

A ratio compares two or more amounts, like 3 : 2, and proportion keeps that comparison fixed as the amounts grow or shrink — the same idea behind sharing money, scaling recipes and reading maps. Pupils most often slip by forgetting to add the ratio parts before dividing the total, sharing the parts in the wrong order, or not simplifying the answer.

At Improve Tuition, a qualified teacher makes the ‘parts’ idea concrete and gives one dependable method for sharing and scaling, in small worked steps — with read-aloud, comfort spacing and a reading tint for pupils who take in maths more easily that way.

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Lesson 1

What a ratio is

Aim: Read and write a ratio, knowing that it compares parts and that order matters.

A ratio compares amounts. 2 : 3 (say “2 to 3”) means that for every 2 of the first thing there are 3 of the second.

Order matters. The ratio of red to blue is not the same as blue to red — write the parts in the order the question gives them.

first · 2second · 3
Two parts to three — for every 2 of the first there are 3 of the second.
Worked example
A team has 2 coaches and 22 players. Write the ratio of coaches to players.
  1. Coaches first, players second: 2 : 22.
  2. Both divide by 2: 1 : 11.
  3. Check: there are still 11 times as many players as coaches. ✓
Watch out
A ratio is not a fraction on its own. 2 : 3 does not mean 2/3 — it means 2 out of every 5. Lesson 4 sorts this out.

Try one

A bag has 3 red and 7 green beads. Write the ratio red : green.

Show answer
Count each colour: 3 red, 7 green.
Write them in order red : green.
3 : 7.
Check: the order matches the question. ✓
Practise this now — Section A →
Lesson 2

Simplifying a ratio

Aim: Write a ratio in its simplest form.

Just like fractions, a ratio simplifies by dividing every part by a common factor, until no single number divides them all.

6 : 9 → divide both by 3 → 2 : 3.
12 : 8 → divide both by 4 → 3 : 2.
6 : 9÷ 3 → 2 : 3
Group in threes — 6:9 is the very same ratio as 2:3.
Worked example
Simplify 20 : 30 : 50.
  1. The biggest number that divides 20, 30 and 50 is 10.
  2. Divide every part by 10.
  3. 2 : 3 : 5.
  4. Check: 2, 3 and 5 share no common factor, so it is fully simplified. ✓
Watch out
Divide every part by the same number. Halving only one side changes the ratio.

Try one

Simplify 45 : 27.

Show answer
Find the biggest number that divides both 45 and 27 — that is 9.
45 ÷ 9 = 5 and 27 ÷ 9 = 3.
5 : 3.
Check: 5 × 9 = 45 and 3 × 9 = 27. ✓
Practise this now — Section A →
Lesson 3

Sharing in a ratio

Aim: Share an amount in a given ratio.

Add the parts to find how many equal shares there are. Divide the amount by that to find one part. Then multiply for each share.

£51 part£5£5£53 parts4 equal parts make £20
Each part is £20 ÷ 4 = £5, so the shares are £5 and £15.
Worked example
Share £20 in the ratio 1 : 3.
  1. Add the parts: 1 + 3 = 4 parts.
  2. One part = £20 ÷ 4 = £5.
  3. Shares: 1 × £5 = £5 and 3 × £5 = £15.
  4. Check: £5 + £15 = £20, the whole amount. ✓
Watch out
The shares must add back to the total: £5 + £15 = £20. If they don’t, check your “one part.”

Try one

Share 60 kg in the ratio 3 : 7.

Show answer
Add the parts: 3 + 7 = 10.
One part = 60 ÷ 10 = 6 kg.
3 parts = 3 × 6 = 18 kg; 7 parts = 7 × 6 = 42 kg.
Check: 18 + 42 = 60. ✓
Practise this now — Section B →
Lesson 4

Ratio and fractions

Aim: Turn a ratio into a fraction of the whole.

Add the parts to get the whole. Each part’s fraction is its number over the total parts.

boys · 3girls · 58 equal parts make the whole class
Girls are 5 of the 8 parts — that is 5/8.
Worked example
In a class the ratio of boys to girls is 3 : 5. What fraction are girls?
  1. Total parts: 3 + 5 = 8.
  2. Girls are 5 parts out of 8.
  3. Girls = 5/8 of the class.
  4. Check: boys are 3/8, and 3/8 + 5/8 = 8/8, the whole class. ✓
Watch out
The bottom of the fraction is the total parts (a + b), not the other number. 2 : 3 gives 2/5, never 2/3.

Try one

In the ratio 1 : 4, what fraction is the first part?

Show answer
Add the parts for the whole: 1 + 4 = 5.
The first part is 1 out of these 5.
First part = 1/5.
Check: 1/5 + 4/5 = 1 whole. ✓
Practise this now — Section C →
Lesson 5

Proportion and scaling

Aim: Scale a quantity up or down using the unitary method.

Find the value of one first, then multiply. That is the unitary method, and it works for recipes, prices, distances and more.

00p1 pen30p3 pens90p5 pens150p
Find one (÷ 3), then multiply up (× 5).
Worked example
3 pens cost 90p. How much do 5 pens cost?
  1. One pen: 90p ÷ 3 = 30p.
  2. Five pens: 5 × 30p = 150p (£1.50).
  3. Check: 5 pens at 30p each is 5 × 30p = 150p. ✓
Watch out
Scale by finding “one,” not by adding on. Going from 4 to 6 people is ×1.5 of everything, not “+2.”

Try one

8 books weigh 2 kg. How much do 20 books weigh?

Show answer
Find the weight of one book first.
2 kg ÷ 8 = 0.25 kg each.
20 books = 20 × 0.25 kg.
= 5 kg.
Check: 8 × 0.25 = 2 kg. ✓
Practise this now — Section D →
↑ Back to the lessons
Section A · Writing & simplifying ratios
LEARNING OBJECTIVE · GRADE 2 · CALCULATION

Write a ratio and give it in its simplest form.

Success criteria — I can:
  • write a ratio in the order asked
  • divide every part by a common factor
  • give a ratio in its simplest form
1.Simplify the ratio 6 : 9.
Answer:
2.Simplify the ratio 12 : 8.
Answer:
3.Simplify the ratio 20 : 30 : 50.
Answer:
4.A box holds 4 red pens and 10 blue pens. Write the ratio red : blue in its simplest form.
Answer:
5.Simplify the ratio 45 : 27.
Answer:
↑ Back to the lessons
Section B · Sharing in a ratio
LEARNING OBJECTIVE · GRADE 3 · CALCULATION

Share an amount in a given ratio.

Success criteria — I can:
  • add the parts
  • find the value of one part
  • multiply to find each share
6.Share £20 in the ratio 1 : 3. How many pounds is the larger share?
Answer:
7.Share 35 sweets in the ratio 2 : 5. How many sweets are in the smaller share?
Answer:
8.Share £48 in the ratio 1 : 2 : 3. How many pounds is the largest share?
Answer:
9.Share 60 kg in the ratio 3 : 7. How many kg is the smaller share?
Answer:
10.£90 is shared in the ratio 4 : 5. How many pounds is the larger share?
Answer:
↑ Back to the lessons
Section C · Ratio and fractions
LEARNING OBJECTIVE · GRADE 3 · CALCULATION

Express a part of a ratio as a fraction of the whole.

Success criteria — I can:
  • add the parts to find the whole
  • write a part as a fraction of the total
  • give the fraction in lowest terms
11.In the ratio 2 : 3, what fraction of the whole is the first part?
Answer:
12.A class has boys and girls in the ratio 3 : 5. What fraction of the class are girls?
Answer:
13.Red and blue counters are in the ratio 1 : 4. What fraction are red?
Answer:
14.A drink mixes squash and water in the ratio 1 : 9. What fraction is squash?
Answer:
15.In the ratio 5 : 7, what fraction of the whole is the second part?
Answer:
↑ Back to the lessons
Section D · Proportion & scaling
LEARNING OBJECTIVE · GRADE 3 · CALCULATION

Scale a quantity using the unitary method.

Success criteria — I can:
  • find the value of one
  • multiply for the new amount
16.3 pens cost 90p. How much do 5 pens cost, in pence?
Answer:
17.A recipe for 4 people needs 200 g of rice. How much rice is needed for 6 people, in grams?
Answer:
18.8 identical books weigh 2 kg. How much do 20 books weigh, in kg?
Answer:
19.A car travels 150 km on 10 litres of fuel. How far does it go on 4 litres, in km?
Answer:
20.6 oranges cost £1.20. How much do 10 oranges cost, in pounds?
Answer:
↑ Back to the lessons
Section E · Real-life ratio problems
LEARNING OBJECTIVE · GRADE 3 · WORD PROBLEM

Solve real-life problems using ratio.

Success criteria — I can:
  • pick out the ratio and the known amount
  • find one part
  • answer the question asked
21.A fruit punch mixes orange juice and lemonade in the ratio 2 : 3. If 400 ml of orange juice is used, how much lemonade is needed, in ml?
Answer:
22.Mortar is made from cement and sand in the ratio 1 : 5. To make 30 kg of mortar, how much sand is needed, in kg?
Answer:
23.Two sisters share £64 in the ratio 3 : 5 by age, with the older getting more. How many pounds does the older sister get?
Answer:
24.On a trip the ratio of adults to children is 1 : 8. If there are 4 adults, how many children are there?
Answer:
25.Paint is mixed blue : white in the ratio 2 : 7. A 36-litre tin holds this mix. How many litres are blue?
Answer:
↑ Back to the lessons
Section F · Proportion problems
LEARNING OBJECTIVE · GRADE 4 · WORD PROBLEM

Solve real-life problems using direct proportion.

Success criteria — I can:
  • find the value of one unit
  • scale up or down
  • include sensible units
26.4 identical cakes need 600 g of flour. How much flour is needed for 10 cakes, in grams?
Answer:
27.A map uses a scale of 1 cm : 5 km. Two towns are 7 cm apart on the map. How far apart are they really, in km?
Answer:
28.A printer prints 24 pages in 3 minutes. How many pages does it print in 8 minutes?
Answer:
29.250 g of cheese costs £2. How much does 600 g cost, in pounds?
Answer:
30.A 12 m² wall needs 3 tins of paint. How many tins are needed for a 28 m² wall?
Answer:
↑ Back to the lessons
Section G · Multi-step reasoning
LEARNING OBJECTIVE · GRADE 5 · WORD PROBLEM

Work backwards and combine steps with ratio.

Success criteria — I can:
  • use one known part to find the value of a part
  • use a difference or total to find the parts
  • check the answer fits the ratio
31.Two quantities are in the ratio 3 : 4. The larger part is 28. What is the smaller part?
Answer:
32.Two numbers are in the ratio 5 : 8 and add up to 91. What is the larger number?
Answer:
33.In a shelter the ratio of cats to dogs is 4 : 3. There are 12 more cats than dogs. How many dogs are there?
Answer:
34.5 machines fill 200 bottles in an hour. At the same rate, how many bottles would 8 machines fill in an hour?
Answer:
35.A recipe serves 6 and uses 450 g of flour. Jamie has 750 g of flour. What is the largest number of whole servings he can make?
Answer:
0 of 35 answered
Guide

What is the difference between ratio and proportion?

A ratio compares quantities, written with a colon, such as 3 : 2. Proportion is what stays the same when those quantities are scaled together — if a recipe uses flour and sugar in the ratio 3 : 2, doubling both keeps the proportion the same.

To share in a ratio, add the parts to find the total number of shares, divide the amount by that number to find one share, then multiply for each side. To simplify a ratio, divide every part by the same number, just like a fraction.

Common mistakes. Dividing by one part instead of the total number of parts, matching the shares to the wrong items, or leaving a ratio unsimplified.

Common questions
How do you simplify a ratio?
Divide every part of the ratio by the same number until they share no common factor. For example, 10 : 15 simplifies to 2 : 3.
How do you share an amount in a ratio?
Add the parts to get the total number of shares, divide the amount by that total to find one share, then multiply by each part. To share £40 in 3 : 1, one share is £10, giving £30 and £10.
What is direct proportion?
Two quantities are in direct proportion when they increase or decrease at the same rate — double one and the other doubles too. The amount per unit stays constant.
What does a ratio like 3 : 2 mean?
For every 3 of the first thing there are 2 of the second. The actual amounts can be any matching multiple, such as 6 and 4, or 30 and 20.
How is ratio linked to fractions?
In the ratio 3 : 2 there are 5 parts altogether, so the first amount is 3/5 of the total and the second is 2/5.
Stuck on this topic?

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