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Time & Work · Question 50 of 61

Question 50

EasyOriginal question

A 900-litre tank already holds 300 litres. An inlet adds 25 litres per minute while an outlet removes 15 litres per minute. With both open, how many minutes will the tank take to fill?

Options for question 50

Show the answer and explanation
CorrectNot quiteAnswer D

Correct answer: D

Explanation

  1. Water still needed = 900−300=600900 - 300 = 600 litres.

  2. Net inflow = 25−15=1025 - 15 = 10 litres per minute.

  3. Time = 600÷10=60600 \div 10 = 60 minutes.

Worth noting

36 minutes fills the whole 900 litres with the inlet alone; 24 minutes ignores the outlet. Use the space left and the net flow.

Concept
Net flow into a partly filled tank
Typical time
40 s
Your time
—
The rule this testsPipes and cisterns
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Ten questions from Time & Work, at your own pace.

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Ten questions from Time & Work, at your own pace.

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