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Year 8 Maths — Direct and inverse proportion

Tell direct proportion from inverse proportion, and use each to find a missing quantity.

Name: ________________________

  1. 1.A journey takes 4 hours at 60 km per hour. How many hours would it take at 80 km per hour?

  2. 2.If 5 pens cost $60, what do 8 pens cost? Give just the number.

  3. 3.y is in inverse proportion to x. When x is 4, y is 15. What is y when x is 10?

  4. 4.6 workers take 12 days to finish a job. Match each number of workers to the days they would take at the same rate.

    • 4 workers
    • 8 workers
    • 9 workers
    • 12 workers
    • 18 workers
    • 8 days
    • 4 days
    • 9 days
    • 6 days
    • 18 days

  5. 5.12 pipes fill a tank in 20 minutes. How many minutes would 15 pipes take?

  6. 6.If 4 kg of rice costs $200, what do 7 kg cost? Give just the number.

  7. 7.6 workers build a wall in 12 days. How many days would 8 workers take, working at the same rate?

  8. 8.A job takes 6 people 12 days. Put these teams in order by how long they would take, shortest first.

    • 12 people
    • 6 people
    • 9 people
    • 4 people
    • 18 people

Answer key — Year 8 Maths — Direct and inverse proportion

  1. 1. 3
  2. 2. 96
  3. 3. 6
  4. 4. 4 workers → 18 days; 8 workers → 9 days; 9 workers → 8 days; 12 workers → 6 days; 18 workers → 4 days
  5. 5. 16
  6. 6. 350
  7. 7. 9
  8. 8. 1. 18 people 2. 12 people 3. 9 people 4. 6 people 5. 4 people