Ratio and proportion

Sharing in a ratio, simplifying ratios, ratio in word problems. Year 7-8.

KS3 ratio extends Year 6: simplifying ratios (12:18 = 2:3 by dividing both by 6), sharing in a ratio (£120 in the ratio 3:5 = £45:£75), comparing as fractions or per-100.

Worked examples

Ratio 12:18 simplifies to 2:3. Divide both by HCF (6).

£120 shared 3:5 = £45 + £75. 8 parts; 1 part = 15.

Recipe for 4 scales to 6: multiply by 1.5. A 200g flour recipe needs 300g for 6 portions.

Frequently asked questions

Ratio or fraction?

Ratio compares parts to parts. Fraction compares part to whole. 3:5 ratio = 3/8 of total is the first portion.

Three-part ratios?

Same logic. £240 in ratio 1:2:3 = 6 parts; 1 part = 40; portions are £40, £80, £120.