At a community centre, a rectangular paddling pool measuring 120 cm by 60 cm by 40 cm was 34 full of water. Pump P took 6 minutes to fill the empty space.
- Find the volume of the empty space in the paddling pool.
- Find how long Pump P would take to fill an empty paddling pool of the same size.
Need a hint?
Find the empty fraction of the pool and the volume that Pump P filled in 6 minutes.
Worked answer
- Find the full volume: 120 × 60 × 40 = 288 000 cm³.
- Find the empty volume: 288 000 × 14 = 72 000 cm³.
- Find Pump P's filling rate: 72 000 ÷ 6 = 12 000 cm³ per minute.
- Fill an empty pool: 288 000 ÷ 12 000 = 24 minutes.
Answer: 24 minutes
The mistake this question tests
Habit
Fraction of a remainder
Some pupils think the 6 minutes filled 34 of the pool and get 6 ÷ 34 = 8 minutes. The 6 minutes filled only the empty 14 of the pool.
How to fix it at home →Wrong answers children often give:
- 6 Fraction of a remainder
- 8 Fraction of a remainder
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