Direct and inverse proportion

What you'll learn

1. 1

   Imagine you're buying 🍬 sweets. 1 bag costs £2. 2 bags cost £4. 3 bags cost £6. As you buy more bags, the total cost goes up by the same amount each time.

2. 2

   If 1 bag of sweets costs £2, how much do 4 bags cost?

3. 3

   Drag the slider to see how the cost changes as you buy more bags. 1 bag = £2. The line shows it's a straight line through 0.

4. 4

   3 books cost £12. How much do 5 books cost? (Assume direct proportion)

5. 5

   Now imagine painting a fence. 1 painter takes 6 hours. 2 painters take 3 hours. 3 painters take 2 hours. As the number of painters goes up, the time goes DOWN.

6. 6

   Drag to see how many hours 4 painters take if 1 painter takes 6 hours. The product (painters × hours) is always 6.

7. 7

   4 painters take 1.5 hours. How many hours would 6 painters take? (Hint: painters × hours is always 6)