Ratio, Proportion and Rates of Change
The complete ratio and proportion curriculum for ages 10 to 16, with every topic taught in its own bite-sized video lesson. Steady, confident progress from the basics up, with an AI tutor to help whenever you get stuck.
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Explore every Ratio and Proportion topic
Ratios, proportion, percentages and compound interest. Build each skill with guided videos and worked practice examples.
Ratios
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Proportion
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Directly Proportional and Inversely Proportional
Direct and inverse proportion side by side: y = kx rises together, y = k/x goes the other way.
Direct Proportion Formula and Examples
Doubling one quantity doubles the other: 1 watermelon costs £4, so 5 cost £20.
Inverse Proportion Formula and Examples
Inversely proportional means one doubles as the other halves: twice the workers, half the time.
Percentages and Interest
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Fractions and Percentages
Fraction to percentage: multiply by 100, so 3/5 = 60%, and 45% = 45/100 = 9/20.
How to Find Percentage of a Number
How to work out percentage of a number: 10% of 80 is 8, so 35% of 80 is 3 × 8 + 4 = 28.
Percentage Increase and Decrease
How to calculate percentage increase with a multiplier: a 20% rise is × 1.2, a 20% drop is × 0.8.
How to Calculate Percentage Change
The percentage change formula is change ÷ original × 100, so £40 to £50 is a 25% rise.
Interest and Interest Rate Calculation
How to calculate interest: £500 at 4% a year earns £20, and the rate is interest ÷ amount × 100.
Simple Interest and Compound Interest
The compound interest formula multiplies by (1 + r) each year: £100 at 10% is £121 after two years.
Compound Measures
Speed, Distance and Time
The speed distance time triangle: speed = distance ÷ time, so 90 miles in 2 hours is 45 mph.
Density, Mass and Volume
The density formula is density = mass ÷ volume, so 200 g in 50 cm³ is 4 g/cm³.
Pressure, Force and Area
The pressure formula is pressure = force ÷ area, so 60 N on 2 m² is 30 N/m².
Explore other Maths categories
Maths Angel covers the whole maths curriculum for ages 10 to 16. Ratio, Proportion and Rates of Change is one of six categories, so jump into any of the others.