9514 1404 393
Answer:
42,412 ft³ each tank
84,823 ft³ both tanks added together
Step-by-step explanation:
"Congruent in size" means both tanks have the same dimensions. Each has a radius of 15 ft and a length of 120 ft. Each has half the volume of a cylinder with those dimensions.
The formula for the volume of a cylinder is ...
V = πr²h
where r is the cylinder radius, and h is the length of its axis.
We want the volume of half a cylinder with r=15 and h=120 (dimensions in ft). We can compute that using ...
V = 1/2π(15 ft)²(120 ft) = π(225 ft²)(60 ft)= 13500π ft³
If we want the volume to the nearest cubic foot, we need a value of pi that is at least 7 significant digits (3.14 isn't appropriate). Then the volume is about ...
(13,500)(3.141593) ft³ ≈ 42,411.5 ft³ ≈ 42,412 ft³
Both tanks have a volume of 42,412 ft³ each.
_____
Additional comment
The question, "What is the volume of both tanks?" is ambiguous. We're not sure if the combined volume is intended, or if the volume of each of the two tanks is intended. Both numbers are provided, so you can sort it out as you see fit.
