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Compound measures combine two quantities, such as speed, density and pressure. This topic calculates with them and converts their units. It's a core topic in GCSE and iGCSE Maths with Edexcel and the other major boards. This free interactive eClassroom course walks through each step with worked examples and instant-feedback questions, so you can practise until it's secure.
How you do it
Identify the two quantities being combined and write the formula as one divided by the other. Convert all units to match before substituting, and give the answer with the compound unit attached.
Before you start
The groundwork here is speed, distance and time, and units. It reappears throughout density, pressure and rate questions. It is Foundation and Higher tier material at GCSE and iGCSE.
What you learn
A compound measure combines two quantities into a single rate — pay per hour, litres per minute, people per km². A rate tells you how much of one quantity there is for each unit of another. A flow rate measures volume per unit of time, such as litres per minute. Population density = population ⁄ area, measured in people per km². The course works through rates and rate of pay, flow rate and fuel consumption and population density and other rates. Every section has instant-feedback practice questions matched to Edexcel iGCSE 4MA1 and the other major GCSE boards, and the course finishes with full exam-style questions you mark yourself.
Related Topics
In our GCSE maths courses, Compound Measures belongs to Ratio and Proportion and is met in Foundation tier. The course is built from 3 concept sections, 2 worked examples and 3 check points before the exam-style set. Students often pair it with Density & Pressure, Direct & Inverse Proportion, Exchange Rates & Best Value and Growth & Decay. You can drill this strand further on the Ratio and Proportion revision engine, with your accuracy saved to your skill tree.
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