What is the approximate volume of a cylinder if the cylinder is 13 feet tall with a circumference of 4.5 feet?

Answer 1

The way I remember the equation for the volume of a cylinder is by thinking of it as a circle with height. The area of a circle is pi x r^2, so the volume of a cylinder is pi x r^2 x h. We need to derive r from the circumference. Since pi is the ratio of any circle's circumference to its diameter, just divide the circumference by pi to get the diameter, then divide that by 2 to get the radius. So the radius is (2.25/pi) ft. When we square that, we have (5.0625/pi^2) ft^2. Multiplying that by pi gives us (5.0625/pi) ft^2. Multiplying by the height makes it (65.8125/pi) ft^3, which is roughly 21 cubic feet.

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Answer 2

20.95 cubic feet, approx (20.9 to 3 sig fig).