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Question
A cylindrical tank full of water is emptied by a pipe at the rate of 225 litres per minute. How much time will it take to empty half the tank, if the diameter of its base is 3 m and its height is 3.5 m? [Use \[\pi = \frac{22}{7}\]]
Solution
Volume of cylidrical tank = \[\frac{22}{7} \times \left( \frac{3}{2} \right)^2 \times 3 . 5\] =24.75 m3
Now, 1 m3 = 1000 L
∴ 24.75 m3 = 24750 L
Half the capacity of tank = 12375 L
Time taken by the pipe to empty 225 litres = 1 minute
Time taken by the pipe to empty 1 litre = \[\frac{1}{225}\] minutes
Time taken by the pipe to empty 12375 litres = \[\frac{1}{225} \times 12375 = 55 \text { minutes }\]
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