So,
Congruent tanks implies that both tanks are of identifical shape, form & dimensions. Congruent means that the tanks have the same radius as well as height. Hence, the heights and radius of tanks #1 and #2 are equal and the same.
Now:
- radius(tank #1) = 15 ft ⇒ radius(tank #2) = 15 ft
- height(tank #2) = 120 ft ⇒ height(tank #1) = 120 ft
The volume of a cylinder is given by the equation:
[tex]V=\pi\cdot r^2\cdot h[/tex]
As the tanks have been cut into half, we got that the volume of each tank is:
[tex]V=\frac{1}{2}\pi\cdot r^2\cdot h[/tex]
The volume of both tanks is the sum of the volume each one, so:
[tex]\text{TotalVolume=VTank1+Vtank2}_{}[/tex]
Both are cogruent so we could write:
[tex]\text{Total}=\frac{1}{2}\pi\cdot r^2\cdot h+\frac{1}{2}\pi\cdot r^2\cdot h=\pi\cdot r^2\cdot h[/tex]
If we replace:
[tex]TotalVolume=\pi\cdot(15ft)^2(120ft)=84823.002ft^3[/tex]