Answer to Question #302525 in Geometry for RAFAEL

Question

The sidewall of a cylindrical tank of radius 30 cm and height of 1 m should be lined with a 4 cm thick layer of concrete.

The sidewall of a cylindrical tank of radius 30 cm and height of 1 m should be lined with a 4 cm thick layer of concrete.

Calculate the volume of the cylinder

Answer: What is approximately the amount of concrete required?

Answer 1

Volume of the tank: $V_1=\pi r^2h=\pi*0.3^2*1=0.09\pi \;m^3.$

Volume of the tank with concrete: $V_2=\pi (r+0.04)^2h=\pi*0.34^2*1=0.1156\pi\;m^3$ .

Volume of the concrete: $V=V_2-V_1=0.1156\pi-0.09\pi=0.0256\pi\;m^3\approx 0.08\;m^3.$