Ratio (introduction)
Ratio compares two amounts: 3:1, 5:2 etc. Year 6 introduces; KS3 develops.
Year 6 SATs include ratio word problems: a recipe, a pot of money divided in a ratio, scaling pictures. The notation 3:1 means ‘for every 3 of A, there is 1 of B’.
Worked examples
Squash 1:5 means 1 part squash to 5 parts water. 200ml squash needs 1000ml water.
Pizza shared 3:2 between two children: 8 slices ⇒ 5 parts ⇒ one part = 8÷5 = ... ratios that don't divide evenly are KS3.
£30 in the ratio 2:3 = £12 : £18. 5 parts total: 30÷5 = 6; 2×6=12, 3×6=18.
Frequently asked questions
Is ratio the same as fraction?
Related but not identical. Ratio 3:2 means 3 of one to 2 of the other. As a fraction of total: 3/5 are A, 2/5 are B.
3:2 vs 2:3?
Order matters. 3:2 of A:B is the inverse of 2:3 of A:B.