Revision notes · Maths
A ratio compares quantities. To simplify a ratio, divide all parts by their HCF — just like simplifying a fraction.
Sharing in a ratio is a very common exam question. Here's the method:
1. Add up the total parts
2. Divide the total amount by the total parts to find the value of one part
3. Multiply each ratio part by the value of one part
You might also be given one share and asked to find the total. In that case, work out the value of one part first, then multiply by the total number of parts.
To combine two ratios that share a common element (e.g., a:b and b:c), find a common multiple for that element and scale both ratios so that the common element has the same value in each ratio. Then, you can write the combined ratio.