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Year 9 Maths — Direct and inverse proportion

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

Name: ________________________

  1. 1.If 5 pens cost £60, what do 8 pens cost? Give just the number.

  2. 2.12 pipes fill a tank in 20 minutes. How many minutes would 15 pipes take?

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

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

  4. 4.6 workers build a wall in 12 days. How many days would 8 workers take, working at the same rate?

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

  6. 6.Two quantities are in inverse proportion. Which of these stays the same as they change?

    • a) Their product
    • b) Their difference
    • c) Their ratio
    • d) Their sum

  7. 7.A car travels 180 km in 3 hours at a steady speed. How far does it go in 5 hours, in km? Give just the number.

  8. 8.6 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
    • 9 days
    • 6 days
    • 4 days
    • 8 days
    • 18 days

Answer key — Year 9 Maths — Direct and inverse proportion

  1. 1. 96
  2. 2. 16
  3. 3. 1. 18 people 2. 12 people 3. 9 people 4. 6 people 5. 4 people
  4. 4. 9
  5. 5. 6
  6. 6. a) Their product
  7. 7. 300
  8. 8. 4 workers → 18 days; 8 workers → 9 days; 9 workers → 8 days; 12 workers → 6 days; 18 workers → 4 days