Math CentralQuandaries & Queries


Question from Old:

I have a round kettle I use to make soup for the hungry. I was curious on how many gallons it holds. The radius is 16 inches and the height is 18 inches.


Are you sure your kettle has a radius of 16 inches? That's a huge pot! I am going to assume that the diameter is 16 inches so the radius is 16/2 = 8 inches.


The volume of a cylinder is given by π r2 h where r is the radius, h is the height and π is approximately 3.416. Your measurements are in inches so this will give the volume in cubic inches. You have r = 8 inches and h = 18 inches so that's

π × 82 × 18 = 3619.11 cubic inches.

There are 231 cubic inches in am American gallon so that is

3619.11/231 = 15.67 gallons.

I doubt that you fill the kettle to the top so I suggest that you replace the 18 inch height of the kettle by the height of the soup in the kettle and do the calculations again.

Keep up the good work,

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