Ratio And Proportion

Mix white paint and blue paint in the ratio 3 to 2, then work out what 20 litres of the mixture costs. Buy a 400 gram jar for $3.20 or a 650 gram jar for $5.07 and say which is better value. Work out how many cards you can cut from a thousand centimetres of ribbon. These three questions look like three different subjects and they are all the same idea: quantities that keep a fixed relationship to one another as they change.

You will write ratios and reduce them to their simplest form, see how a ratio connects to a fraction, divide a quantity in a given ratio, and apply ratio to problems that do not announce themselves as ratio problems. You will use common measures of rate, including rates of pay and best-buy comparisons, and solve problems involving direct and inverse proportion, including repeated proportional change. On the Extension Tier you will meet exponential growth and decay, where the multiplier itself is the model.