Find the height of a cylinder with a surface area of 108 pi square meters. the radius of the cylinder is twice the height.

Assuming the cylinder is closed at both ends 
Surface area = 2 pi r^2 + 2 pi r h  = 108

now h = r/2 so we have:-

 2pi r^2 +  pi r^2= 108

 3 pi r^2   = 108
r^2 = 11.459
r =  3.385 
so the height h = 1.693 m to nearest thousandth

Hello!
volume of sphere =4/3.pi.r^3