A ratio shows the relationship between two quantities.
It is written in the form a:b which is read as ‘a to b’.
Jon has a pack of sweets. He shares them with a friend in the ratio 3:2. This means that for every three sweets John eats, he gives his friend two.
If Jon eats 15 sweets (5 × 3), his friend will receive 10 sweets (5 × 2).
In the example, this means that Jon has 5 lots of 3 sweets so his friend will have 5 lots of 2 sweets.
Bread is made using five parts of flour to three parts liquid.
a) Write down the ratio of liquid to flour.
b) If the recipe calls for 200 g of flour, how much liquid will be needed?
As the question asks for the ratio of liquid to flour, you must write the number of parts of liquid first, followed by flour.
b) Five parts = 200
One part = 200 ÷ 5 = 40
Three parts = 3 × 40 = 120
120 ml of liquid will be needed.
Cookies are made using the ratio 3:2:1 of flour, fat and sugar.
If a recipe calls for 150 g of flour, how much fat and sugar are needed?