Question 1002222
the volume of a cylindrical prism is v = pi * r^2 * h


v is the volume
pi is the constant of 3.14.....
r is the radius
h is the height.


you are given the external dimensions of the cylinder as:


r = 3 meters
height = 8 meters.


you are also given that the thickness of the concrete walls is 1 decimeter.


you need to convert decimeters to meters or meters to decimeters.


from the conversion charts, you get 1 decimeter = 1/10 of a meter = .1 meters.


you also get 1 meter = 10 decimeters.


we'll convert everything to meters.


your outer dimensions are:


h = 8 meters
r = 3 meters.
thickness of the wall is 1 decimeter = .1 meters.


your inner dimensions are:
h = 8 meters (no change here)
r = 2.9 meters (subtract .1 meter from 3 meters to get 2.9 meters)


the volume of the external dimensions of the tank is equal to pi * 3^2 * 8 which is equal to 72 * pi cubic meters.


the volume of the internal dimensions of the tank is equal to pi * (2.9)^2 * 8 which is equal to 67.28 * pi cubic meters.


the volume of the concrete wall is there the difference which is 72 * pi minus 67.28 * pi = 4.72 * pi.


your solution is:


the volume of the concrete walls, rounded to the nearest cubic meters, is equal to 5.