Year 7 Maths — The unitary method
Find the value of one thing first, then scale it to any number — and tell direct proportion from inverse.
Name: ________________________
1.12 identical bricks weigh 30 kg. What do 20 of those bricks weigh, in kilograms?
2.More workers finish the same job in less time. That relationship is called...
- a) direct proportion
- b) no proportion at all
- c) a ratio in its simplest form
- d) inverse proportion
3.Which of these pairs are in direct proportion?
- a) The speed of a car and the time it takes on a fixed journey
- b) The number of pens bought and the total cost
- c) The number of taps filling a tank and the time it takes
- d) The number of workers and the days needed to finish a job
4.Sort each pair of quantities by the way they vary together.
Groups: Direct proportion · Inverse proportion
- Number of taps filling a tank and the time taken
- Number of workers and the days to finish a job
- Distance travelled and time taken at a steady speed
- Weight of rice bought and its cost
- Number of books bought and the total cost
- Speed of a car and the time for a fixed journey
5.If 5 notebooks cost $150, what do 8 notebooks cost? Give just the number.
6.A store of food lasts 20 cows for 6 days. How long would the same store last 15 cows, in days?
7.A machine fills 350 bottles in 5 minutes. How many bottles does it fill in 8 minutes?
8.A car travels 240 km in 4 hours. How far does it travel in 1 hour, in kilometres?
Answer key — Year 7 Maths — The unitary method
- 1. 50
- 2. d) inverse proportion
- 3. b) The number of pens bought and the total cost
- 4. Number of books bought and the total cost → Direct proportion; Number of taps filling a tank and the time taken → Inverse proportion; Distance travelled and time taken at a steady speed → Direct proportion; Speed of a car and the time for a fixed journey → Inverse proportion; Number of workers and the days to finish a job → Inverse proportion; Weight of rice bought and its cost → Direct proportion
- 5. 240
- 6. 8
- 7. 560
- 8. 60