Question 713125:  An inverted conical tank of radius 3 meters and altitude of 9 meters contains water to a depth of 3 meters. How much water must be added into the tank such that the depth of water will be doubled? 
 Answer by KMST(5328)      (Show Source): 
You can  put this solution on YOUR website! The tank volume is radius squared times pi, times height, divided by 3. 
In cubic meters, that is 3 squared, times pi, times 9, divided by 3, 
which calculates to 27pi 
The water in the tank occupies a similar cone,  
with all dimensions proportionally smaller by a factor of 3. 
That volume is smaller by a factor of 3 cubed, or 27. 
So the volume of water in the tank is pi cubic meters. 
The volume when the water is twice as deep is the volume of a similar cone, 
2 times as large in all dimensions. 
That makes the volume larger by a factor of 2 cubed, or 8. 
The amount of water that needs to be added is 7 times what is in the tank, 
or 7pi cubic meters. 
That is about 22 cubic meters, which is 22,000 liters. 
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