- A20 min
- B50 min
- C15 min
- D30 min
Step-by-Step Solution
Needed: 60% of 1,000 = 600 L at a net 20 L/min → 30 min. (20 min ignores the outlet; 50 min starts from empty.)
Answer: D) 30 min
A tank holding 1,000 litres has an inlet of 30 litres per minute and an outlet of 10 litres per minute. It is 40% full when both are opened. How long until it is full?
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