AlgebraEasy–MediumEquation for a draining pool
Algebra practice question
A pool holds 12,000 litres of water and drains at a constant 400 litres per minute. Which equation gives the volume V, in litres, remaining after t minutes of draining?
- A. V = 12,000 − 400tCorrect
- B. V = 12,000 + 400t
- C. V = 400 − 12,000t
- D. V = 12,000t − 400
Answer: A. V = 12,000 − 400t
Start full and lose 400 each minute.
Why the other answers are wrong
- B. V = 12,000 + 400t
- Adding would fill the pool.
- C. V = 400 − 12,000t
- The start and the rate are swapped.
- D. V = 12,000t − 400
- The start is multiplied by t.
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