Step-by-step explanation:
the volume of any regular 3D shape is
ground area × height
just as simple as that.
the ground area of a cylinder is a circle.
the area of a circle is
pi × r²
with r being the radius (which is half of the diameter).
1.
r = 11/2 = 5.5 cm
volume = pi×(5.5)²×12 = pi×30.25×12 = 1,140.398133... cm³
2.
r = 21/2 = 10.5 cm
volume = pi×(10.5)²×12 = pi×110.25×12 = 4,156.327081... cm³
3.
r = 6 cm
volume = pi×6²×15 = pi×36×15 = 1,696.460033... cm³
4.
r = 23/2 = 11.5 cm
volume = pi×(11.5)²×25 = pi×132.25×25 =
= 10,386.89071... cm³