Explanation:
the volume of a cylinder is
base area × height.
and the base is a circle, and the area of a circle is
pi×r²
remember, the radius is half the diameter.
so, in our case, the volume is
pi×(18/2)²×20 = pi×9²×20 = pi×81×20 = pi×1620 =
= 5,089.380099... in³ ≈ 5,089 in³