
Rich G. answered 04/02/19
Experienced Geometry Tutor
The equation for the volume of a cylinder is:
V = πr2h
Your question asks about the diameter, and since diameter = 2r, we can rewrite the above equation as:
V = π(d/2)2 h
Or
V = π (d2/4) * h
Now, if the diameter is multiplied by 1/2, the equation would be
V = π [(1/2d)2/4] * h
which becomes
V = π [(1/4*d2)/4] * h
V = π (1/16 d2) * h
When we compare that to the original equation V = π (d2/4) * h we can see the new equation is 1/4 the size of the original one.
So when the diameter is reduced by 1/2 the volume is reduced by 1/4