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Writing & simplifying ratio practice questions with answers

Foundation and Higher · Grade 3

A second set of writing & simplifying ratio questions for GCSE Maths. They are different from the ones on the topic page, so work through both. Try each question, then open the answer to check your working.

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Question 1 Easy

Write the ratio 15:18 in its simplest form.

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Answer: 5:6

  1. The highest common factor of 15 and 18 is 3.
  2. 15 ÷ 3 = 5 and 18 ÷ 3 = 6.
  • Method (1): The highest common factor of 15 and 18 is 3.
  • Accuracy (1): Answer 5:6

Question 2 Easy

Write the ratio 12:28 in its simplest form.

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Answer: 3:7

  1. The highest common factor of 12 and 28 is 4.
  2. 12 ÷ 4 = 3 and 28 ÷ 4 = 7.
  • Method (1): The highest common factor of 12 and 28 is 4.
  • Accuracy (1): Answer 3:7

Question 3 Medium

Write the ratio 12:27 in its simplest form.

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Answer: 4:9

  1. The highest common factor of 12 and 27 is 3.
  2. 12 ÷ 3 = 4 and 27 ÷ 3 = 9.
  • Method (1): The highest common factor of 12 and 27 is 3.
  • Accuracy (1): Answer 4:9

Question 4 Medium

Write the ratio 20 cm to 2 m in its simplest form.

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Answer: 1:10

  1. Change 2 m into centimetres: 2 × 100 = 200 cm.
  2. The ratio is 20:200, and the highest common factor is 20.
  • Method (1): Change 2 m into centimetres: 2 × 100 = 200 cm.
  • Accuracy (1): Answer 1:10

Question 5 Hard

Write the ratio 80 cm to 1 m in its simplest form.

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Answer: 4:5

  1. Change 1 m into centimetres: 1 × 100 = 100 cm.
  2. The ratio is 80:100, and the highest common factor is 20.
  • Method (1): Change 1 m into centimetres: 1 × 100 = 100 cm.
  • Accuracy (1): Answer 4:5

Question 6 Hard

Write the ratio 12:30 in its simplest form.

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Answer: 2:5

  1. The highest common factor of 12 and 30 is 6.
  2. 12 ÷ 6 = 2 and 30 ÷ 6 = 5.
  • Method (1): The highest common factor of 12 and 30 is 6.
  • Accuracy (1): Answer 2:5

Exam-style question

A longer question with marks, in the style of a written paper. This is a Yumio practice question, not a past paper question.

Exam-style question 12 marks

Write the ratio 21:35 in its simplest form.

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Answer: 3:5

  1. The highest common factor of 21 and 35 is 7.
  2. 21 ÷ 7 = 3 and 35 ÷ 7 = 5.
  3. The simplest form is 3:5.
  • Method (1): The highest common factor of 21 and 35 is 7.
  • Accuracy (1): Answer 3:5

Quick checks

Short one-step questions. Pick an option before you open the answer.

Check 1

Write the ratio 28:36 in its simplest form.

  1. 7:9
  2. 7:36
  3. 9:7
Show answer

7:9 The result is 7:9.

Check 2

Write the ratio 20:45 in its simplest form.

  1. 4:9
  2. 4:45
  3. 9:4
Show answer

4:9 The result is 4:9.

Check 3

Write the ratio 75 cm to 2 m in its simplest form.

  1. 3:8
  2. 75:2
  3. 8:3
Show answer

3:8 The result is 3:8.

Check 4

Write the ratio 49:56 in its simplest form.

  1. 7:8
  2. 7:56
  3. 8:7
Show answer

7:8 The result is 7:8.

Check 5

Write the ratio 12:18 in its simplest form.

  1. 2:3
  2. 2:18
  3. 3:2
Show answer

2:3 The result is 2:3.

Check 6

Write the ratio 45 cm to 1 m in its simplest form.

  1. 9:20
  2. 45:1
  3. 20:9
Show answer

9:20 The result is 9:20.

Check 7

Write the ratio 16:40 in its simplest form.

  1. 2:5
  2. 2:40
  3. 5:2
Show answer

2:5 The result is 2:5.

Check 8

Write the ratio 27:45 in its simplest form.

  1. 3:5
  2. 3:45
  3. 5:3
Show answer

3:5 The result is 3:5.

Check 9

Write the ratio 35 cm to 2 m in its simplest form.

  1. 7:40
  2. 35:2
  3. 40:7
Show answer

7:40 The result is 7:40.

Check 10

Write the ratio 35:42 in its simplest form.

  1. 5:6
  2. 5:42
  3. 6:5
Show answer

5:6 The result is 5:6.

Check 11

Write the ratio 24:56 in its simplest form.

  1. 3:7
  2. 3:56
  3. 7:3
Show answer

3:7 The result is 3:7.

Check 12

Write the ratio 90 cm to 1 m in its simplest form.

  1. 9:10
  2. 90:1
  3. 10:9
Show answer

9:10 The result is 9:10.

Check 13

Write the ratio 42:54 in its simplest form.

  1. 7:9
  2. 7:54
  3. 9:7
Show answer

7:9 The result is 7:9.

Check 14

Write the ratio 28:63 in its simplest form.

  1. 4:9
  2. 4:63
  3. 9:4
Show answer

4:9 The result is 4:9.

Check 15

Write the ratio 15 cm to 2 m in its simplest form.

  1. 3:40
  2. 15:2
  3. 40:3
Show answer

3:40 The result is 3:40.

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