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[h] Year 6 Maths Ratio and Proportion Study Flashcards
[q] Understanding Ratio
A ratio is the quantitative relationship between two amounts.
[a] ‘The ratio of boys to girls in the class is 1 : 2’ means for every one boy there are two girls.
Example
Emily is threading beads onto a necklace. For every one red bead, she puts on two blue beads. Ratio of red to blue beads = 1 : 2 She has five red beads and nine blue beads. Can she continue her necklace in the ratio of 1 red : 2 blue?
No – she needs another blue bead. You can work out how many blue beads she needs to match five red beads. To get from 1 to 5, you multiply the red side by 5 so you must do the same to the blue side: 2 × 5 = 10 Ratio of red to blue = 5 : 10
[q] Simplifying Ratios
You can simplify ratios in the same way you simplify fractions.
[a] Example
To simply 6 : 18 you need to look for something you can divide both sides by. This is where your multiplication and division facts come in handy! So 6 : 18 simplifies to 1 : 3
You can scale up ratios too. This means you can work out how many of something there are from a given ratio.
The ratio of boys to girls in a class of 32 children is 3 : 5. So, there are 12 boys and 20 girls.
Tanisha draws a triangle. The ratio of the sides is 3 : 4 : 8. She then draws a triangle six times bigger. What are the lengths of the sides of the new triangle?
The side lengths of the new triangle are 18 : 24 : 48
[q] Ratio Tables
You can use ratio tables to help set out your work logically.
[a] Example
Jane made a smoothie with a ratio of 2 bananas : 3 apples. How many apples will she need if she uses 12 bananas? By experimenting with the top row and doing the same to the bottom row, you can find out how many apples Jane would need. She will need 18 apples.
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