You must find the area of the circle first, meaning you need to find the Radius. The radius is half of the diameter so:
R = 12
To find the area of a circle you must do (R)^2 x Pi (3.14)
Meaning you must do:
12 x 12 = 144 = (R)^2
144 x (3.14) Pi = 452.16
Next we need to find the volume of the tank, by using the area of the circle we can now use the formula Area ((R)^2 xPi (3.14)) x height
We know the height equals 30dm so:
452.16 x 30 = 13,564.8
As it is 1dm^3 to 1L we don’t need to divide anything to equal them as they are the same meaning the answer is
13,564.8 Litres