Ratio meaning

A ratio is a way of comparing two or more quantities.
It tells us how much of one thing there is compared to another thing.
For example, we could have a ratio which tells us how many apples there are compared to how many oranges there are.
Importantly, they don’t tell us the actual amounts of each thing, just how their amounts compare to each other.

Writing ratios

If we know that we have n apples and m oranges, we can write the ratio of apples to oranges as n:m.
For example, if we have 3 apples and 5 oranges, we can write the ratio of apples to oranges as 3:5.
This could also be written in any equivalent form. For example, the 3:5 apples to oranges ratio could also be written as 6:10 or 9:15, for example.
To find equivalent ratios, we can multiply or divide both sides of the ratio by the same number - see simplifying ratios for more details.

The ratio of pears to bananas is 2:3.
We can see that each part pear is equal to 4 actual pears, because:
- 8 \div 2 = 4
To keep the ratio the same, we need to multiply the number of bananas by 4 as well:
3 \times 4 = 12
Answer: there are 12 bananas.

The ratio of boys to girls is 5:4.
We can see that each part boy is equal to 4 actual boys, because:
- 20 \div 5 = 4
To keep the ratio the same, we need to multiply the number of part girls by 4 as well:
- 4 \times 4 = 16
Answer: there are 16 girls.

This was probably the most awkwardly worded example I’ve ever written.

Question	Answer
What is a ratio?	A way of comparing two or more quantities; it tells how much of one thing there is compared to another, but not the actual amounts.
How do you write the ratio of n apples to m oranges?	n:m
If there are 3 apples and 5 oranges, what is the ratio of apples to oranges?	3:5
How can a ratio like 3:5 be rewritten?	In any equivalent form e.g. 6:10 or 9:15.
How do you find equivalent ratios?	Multiply or divide both sides of the ratio by the same number.
A fruit bowl has pears and bananas in ratio 2:3. If there are 8 pears, how many bananas are there?	Each part pear equals 8 \div 2 = 4 actual pears, so bananas are 3 \times 4 = 12.
A classroom has boys and girls in ratio 5:4. If there are 20 boys, how many girls are there?	Each part boy equals 20 \div 5 = 4 actual boys, so girls are 4 \times 4 = 16.