A cylinder has a surface area of 250cm2

Question

. The height is twice as big as the radius. What is the
height of the cylinder?

Answer 1

V = πr^2 h, but h = 2r
so
V = πr^2 (2r)
= 2πr^3

then 2πr^3 = 250
r^3 = 125/π
r = cuberoot(125/π)
h = 2r = 2 cuberoot(125/π) = appr 6.83 cm