Ratio (GCSE)
Simplifying ratios, sharing in a ratio, ratio ↔ fractions, three-part ratios.
GCSE ratio extends KS3: simplifying with units (1m : 50cm = 100 : 50 = 2 : 1), three-part ratios, and conversion ratio ↔ fraction. Common exam: a recipe scaling problem.
Worked examples
32 : 24 = 4 : 3. Divide both by HCF (8).
£180 in 3:5:4 = £45 + £75 + £60. 12 parts; 1 part = 15.
3 : 7 means 3/10 are A, 7/10 are B.
Frequently asked questions
Three-part?
Sum the parts to find the unit. 3+5+4 = 12 parts; total ÷ 12 = one part.
Ratios with different units?
Convert to the same unit first. 1 m : 50 cm = 100 cm : 50 cm = 2 : 1.