Question 791382
The volume of a cylinder of radius {{{r}}} and height {{{h}}} is calculated as
{{{pi*r^2*h}}}
To calculate the volume of the material in a tube of length 20 cm, with an inner radius of 3 cm and an outer radius of 5 cm, we calculate
the volume of a cylinder with a height of 20 cm and a radius of 5 cm,
and subtract
the volume of a cylinder with a height of 20 cm and a radius of 3 cm.
The result, in cubic centimeters, is
{{{pi*5^2*20h-pi*3^2*20=pi*20*(5^2-3^2)=pi*20=(25-9)=pi*20*16=highlight(320pi=about1005)}}}