1. My bike’s fuel has a ratio of
oil to petrol
1 : 25
Sounds complicated

2. Using the simplest ratio to describe different quantities.
Sue is explaining how to use a ratio to describe red and green hearts.

3. Count the number of red and green hearts 4 RED and 8 GREEN
Record the numbers using headings like this
Red : Green
4 : 8
The : says ‘to’

4. Try to write the ratio in its simplest terms
Red : Green
4 : 8
2 : 4
1 : 2
Divide ÷ by 2

5. The ratio of red to green is Red : Green 1 : 2
This tells you that there are 2 green hearts for every red heart

6. Copy and complete this chart
Ratio
Simplest terms
12 : 16
24 : 32
27 : 36
28 : 40

7. Copy and complete this chart
Ratio
Simplest terms
12 : 16
3 : 4
24 : 32
27 : 36
28 : 40
7 : 10

8. For example, share 36 into the ratio 2 : 7
Sharing a quantity into a given ratio
For example, share 36 into the ratio 2 : 7
First ADD the ratio = 9
Second DIVIDE this answer into the quantity to be shared 36 ÷ 9 = 4
Third MULTIPLY the ratio by this answer 2 X 4 : 7 X 4
This is the answer 8 : 28

9. + ÷ X To share into a given ratio, the things to do are:
Share 32 into the the ratio 3 : 5
3 + 5 = ÷ 8 = 4
3 X 4 = 12 : 5 X 4 = 20
Answer 12 : 20

10. Share these into the given ratio
Quantity
Share
2 : 3 50
2 : 5 28
3 : 7 20
4 : 5
360
1 : 2 : 5 32

11. Share these into the given ratio
Quantity
Share
2 : 3 50
20 : 30
2 : 5 28
8 : 20
3 : 7 20
6 : 14
4 : 5
360
160 : 200
1 : 2 : 5 32
4 : 8 : 20

12. Finding an unknown number that fits a given ratio
Example – If the ratio of red beads black beads is 3 : 5, how many black beads will I need for 21 red beads?
Red : Black
3 : 5
21 : ?

13. First find the number that you multiply 3 by to get 21
Red : Black
3 : 5
21 : ?
X 7

14. Red : Black
3 : 5
21 : 42
X 7
X 7

15. Red : Black 2 : 7 12 : ? Another Example 2 X 6 is 12 so you
multiply 7 by 6 to get the ?
X 6

16. Red : Black
2: 7
12 : 42
X 6
X 6