A cylinder pipe made of metal is 4cm thick. If the internal radius of the pipe is 12cm, find the volume of the metal used in making 4cm of the pipe in terms of pie
the volume of the whole pipe is ... π * (12 cm + 4 cm)^2 * 4 cm
volume of the hollow inside is ... π * (12 cm)^2 * 4 cm
volume of metal is the whole pipe, minus the inside