Find the area of the cross section (looking at it from the side, you can see a circle, right?)
Once you've found this, multiply it by the length of the whole tube.
So...
Area of cross section (area of circle) = πr²
In this case, r is 1.5cm.
So the area is 3.14 x 1.5² = 7.065
Now times this area by the length of the whole tube, which is 18.5cm.
7.065 x 18.5 = 130.7cm³
