Ratio and proportion
Sharing in a ratio, recipes and best buys
Ratio compares amounts. If a squash drink is 1 part cordial to 4 parts water, the ratio is 1 : 4.
Sharing in a ratio
- Add the parts to find the total number of parts.
- Divide the amount by the total parts to find one part.
- Multiply to find each share.
Simplifying: divide both sides by the same number. 12 : 18 = 2 : 3.
Direct proportion: if one amount doubles, so does the other. Find the value of one first (the unitary method).
Worked examples
Example 1. Share £60 in the ratio 2 : 3.
Example 2. A recipe for 4 people uses 300 g of pasta. How much for 6 people?
Example 3. Best buy: 6 eggs for £1.50 or 10 eggs for £2.20?
Top tips and common mistakes
- The order matters: boys : girls = 3 : 4 is not the same as girls : boys.
- Check your shares add up to the total.
- In best buys, compare the price of the same amount (per item, per 100 g, per litre).
Ratio is how I make the perfect pancake mix for the whole family!
Practise
Answer as many as you like. Every question is new, and you get a “correct” tick for each one you get right first time. Use “Show answer” to see a worked solution.
Quiz: earn your stamp
Printable worksheet
Ratio and proportion worksheet. The questions come first and the answers for grown-ups are on the last page, so you can print just the question pages.
Printing is optional. A4 size.