Part 3: Ratio, proportion and rates of change

• International System of Measure, SI units, are the standardised measures used across the world for length, mass and time.
• Speed = Distance / Time
• Density = Mass / Volume
• Scale factors are numbers that tell us how much larger or smaller one shape is to another
• A ratio is a way of expressing one thing compared to another by using parts.
• To scale a ratio, we multiply by a common factor.
• Simple interest is where we increase an original value by a percentage.
• Compound interest occurs when the added interest then also receives interest in subsequent periods.