This study notes covers Worked Example 3: Three-Part Ratio within Ratio Problems for GCSE Mathematics. Revise Ratio Problems in Ratio & Proportion for GCSE Mathematics with 14 exam-style questions and 3 flashcards. This topic shows up very often in GCSE exams, so students should be able to explain it clearly, not just recognise the term. It is section 6 of 8 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Worked Example 3: Three-Part Ratio
Simplify the ratio 15:25:35
Step 1 Find HCF of all three numbers
15, 25, and 35 are all divisible by 5
Step 2 Divide ALL parts by 5
15 ÷ 5 = 3
25 ÷ 5 = 5
35 ÷ 5 = 7
Final Check and write answer
3, 5, 7 have no common factors
15:25:35 = 3:5:7
Practice questions for Ratio Problems
A recipe uses flour and sugar in the ratio 5:2. What fraction of the mixture is flour?
The ratio of apples to oranges in a basket is 2:3. Sarah says "2/3 of the fruits are apples." Explain why Sarah is wrong.