∑ DANEMATHICS
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Grade 9 · Ratio & Proportion
Direct & Indirect Proportion
MEMORANDUM
Name:
Class:
Date:
Mark
/ 16
Answer all questions. Show all your working — marks are awarded for method as well as the final answer. Teacher copy: accept any correct equivalent method.
- 1If 5 books cost R125, what do 8 books cost?(2)One book R25 → R200 (direct)✓✓ (2)
- 2If 3 kg of rice costs R45, what does 7 kg cost?(2)R15/kg → R105 (direct)✓✓ (2)
- 38 workers finish a job in 6 days. How long would 4 workers take?(2)48 ÷ 4 = 12 days (indirect)✓✓ (2)
- 45 taps fill a tank in 12 minutes. How long would 10 taps take?(2)60 ÷ 10 = 6 minutes (indirect)✓✓ (2)
- 5A journey takes 4 hours at 90 km/h. How long at 120 km/h?(2)360 ÷ 120 = 3 hours (indirect)✓✓ (2)
- 6Is 'number of workers vs time taken' direct or indirect?(2)Indirect — more workers, less time.✓✓ (2)
- 7Is 'litres of petrol vs cost' direct or indirect?(2)Direct — more litres, more cost.✓✓ (2)
- 8y is directly proportional to x, and y = 20 when x = 4. Find k.(2)k = 20 ÷ 4 = 5, so y = 5x✓✓ (2)
TOTAL: 16 marks