A ratio tells you how much of one thing there is compared to another.
To make a purple dinosaur we use a ratio of two to three.
That’s two blue dinosaurs, for every three dinosaurs.
Eh hey! We need that!
And what if we want to make an even bigger purple dinosaur? And use eight blue dinosaurs instead of two.
How many red dinosaurs would we need then?
So eight, is two times four.
And to keep the same ratio we can multiply the three red by four as well, which makes 12.
Eight to 12 is the same ratio as two to three, but it’s much bigger.
Four times bigger!
Uh oh! Time to go.
Ratios
A ratio shows how much of one thing there is compared to another. Ratios are usually written in the form a:b.
If you are making orange squash and you mix one part orange to four parts water, then the ratio of orange to water will be 1:4 (1 to 4).
The order in which a ratio is stated is important. Changing the order of the numbers in a ratio changes the proportions.
Simplifying Ratios
The ratio of red to blue dinosaurs is 12:18.
This ratio can be simplified. Both 12 and 18 can be divided by 2.
12 ÷ 2 = 6
18 ÷ 2 = 9
So a simpler way to write 12:18 is 6:9.
The ratio can be simpler again, if we divide by 3.
6 ÷ 3 = 2
9 ÷ 3 = 3
So an even simpler way to write 12:18 is 2:3.
Play Bitesize games
Level up now! Take on the latest primary games on Bitesize.
More on Fractions and decimals
Find out more by working through a topic
- count15 of 16
- count16 of 16
- count1 of 16
