Math CentralQuandaries & Queries


Question from Jordan:

How much water could my well hold if the depth of the well is 30 feet feet and the diameter of the well is 24 feet ?

Hi Jordan,

The volume $V$ of a circular cylinder, which is the shape of your well, is given by

\[V = \pi \; r^2 h\]

where $r$ is the radius of the cylinder and $h$ is its height. Since your measurements are in feet, $V$ will be in cubic feet. I am a Mac user so if I wanted the volume in gallons I would ask Siri "Hey Siri what is $V$ cubic feet in gallons?"

To determine the actual volume of water in the well you would have to use the calculation above with $h$ being the height of the water in the well.


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