A ratio is used to compare two quantities which are measured in the same units. Given a ratio, quantities can be calculated.
Part ofApplications of MathsNumeracy skills
The ratio of girls to boys in the school disco was \(3 : 1\). If there were 50 boys there, how many girls were at the disco?
Boys \(= 1\) part \(= 50\) pupils
Girls \(= 3\) parts \(= 3 \times 50 = 150\) pupils
There were \(150\) girls at the disco.
Now try this question.
The ratio of girls to boys at the school jumble sale was \(1 : 2\).
If there were 20 boys there, how many girls were at the jumble sale?
Boys = 2 parts = 20 pupils, so 1 part = 10 pupils.
Girls = 1 part = 10 pupils.
There were 10 girls at the jumble sale.
