DfE statement R11 · Ratio, proportion and rates of change
Compound units: speed, density, pressure
Compound units: speed, density, pressure is content statement R11 of the DfE GCSE mathematics subject content, in the ratio, proportion and rates of change area. It is on both tiers, and it appears on both the calculator and the non-calculator papers. Below is what the specification actually requires, the 3 mistakes that cost marks on this topic most often, and practice questions written to the statement — original questions, not past papers.
What the specification says
The DfE subject content for GCSE mathematics states, verbatim: "Use compound units such as speed, rates of pay, unit pricing, density and pressure." (statement R11). Every awarding organisation — Pearson Edexcel, AQA and OCR — must cover it, so the wording is the same whichever specification your school follows.
Tier
Both tiers. This statement is Foundation content, which means Higher students are examined on it too — Higher is Foundation plus more, never instead of it.
Calculator
This turns up on both the non-calculator and the calculator papers, so practise it both ways — the written method for Paper 1 and the efficient calculator route for Papers 2 and 3.
Common mistakes
- Rearranging the formula wrongly: speed is distance ÷ time, so time is distance ÷ speed, not speed ÷ distance.
- Mixing units — using a mass in kilograms with a density in g/cm³ without converting.
- Taking the mean of two speeds as the average speed for a whole journey. Average speed is total distance ÷ total time.
Sample questions (10 of 30)
Nearby statements
Questions people ask
Is compound units: speed, density, pressure on Foundation or Higher?
Both. It is Foundation content, so it can be asked on either tier.
Can I use a calculator for compound units: speed, density, pressure?
It depends on the paper. Paper 1 is non-calculator; Papers 2 and 3 allow one, and this topic is asked on both kinds.
What is the single most common mistake here?
Rearranging the formula wrongly: speed is distance ÷ time, so time is distance ÷ speed, not speed ÷ distance.
Are these past paper questions?
No. Every question is original, written to this DfE content statement and checked before publication. We do not host past papers or mark schemes.
Back to Ratio, proportion and rates of change at Foundation or at Higher.