Ratio and rate · Usually met around P6
Sharing in a ratio
Find what one box is worth first.
How to do it
Method
Find what one box is worth first
40 ÷ (2 + 3) = 8 → 16 and 24
Another way
Use fractions
40 × 25 = 16
In full
Think of the ratio as parts and draw a bar model: A : B = 2 : 3, so A gets 2 boxes and B 3 boxes, 5 boxes in all. If the total is 40, each box is 40 ÷ 5 = 8, so A has 2 × 8 = 16 and B has 3 × 8 = 24. If you know one amount instead, say A has 16: A's 2 boxes are 16, so each box is 8, B's 3 boxes are 24 and the total of 5 boxes is 40. If you know the difference: B has 1 box more than A, and that box is the difference. Or use fractions: A is 25 of the whole, and 40 × 25 = 16. Check: 16 + 24 = 40, and 16 : 24 simplifies to 2 : 3.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
The ratio of 🐸 to 🐰 is 3 : 4. There are 15 🐸. How many 🐰 are there?
Show the answer and working
Answer: 20
🐸 has 15 in its boxes, so each box is 15 ÷ 3 = 5; 🐰: 4 × 5 = 20.
Example 2
The ratio of 🧊 to ⭐ to 🐻 is 2 : 1 : 3, with 18 altogether. There are □ 🧊, □ ⭐ and □ 🐻.
Fill in each box
Show the answer and working
Answer: 6，3，9
6 boxes in all, each 18 ÷ 6 = 3: 6, 3 and 9.
Example 3
The ratio of 🐱 to 🍎 is 5 : 6, and there are 2 more 🍎 than 🐱. How many are there altogether?
Show the answer and working
Answer: 22
The gap between 🍎 and 🐱 is 6 − 5 = 1 in boxes, worth 2, so each box is 2 ÷ 1 = 2; all 11 boxes are 22.
Practise it in the game →Ratio and rate · Free to start, unlimited questions, no download