What is the diameter of the tank in feet?

• A. 1,375 ft
• B. 74.5 ft
• C. 42.5 ft
• D. 18.3 ft

Answer: (B)

To find a tank’s diameter from its capacity and height, use the cylinder volume relationship. The volume of a cylinder is V = π r^2 h, where r is the radius and h is the height. Since diameter d = 2r, rewrite in terms of diameter: V = π (d/2)^2 h = (π d^2 h)/4. Solve for diameter: d = sqrt(4V / (π h)).

If the tank’s capacity is given (often in gallons), first convert to cubic feet (1 cubic foot = 7.48052 gallons). Then plug V in cubic feet and h in feet into the formula. Doing the math with the provided values yields a diameter of about 74.5 feet.

This type of problem tests turning a volume requirement into a linear dimension using cylinder geometry. If you mistakenly use radius instead of diameter or mix units, you’d get a different value, which explains why the correct result comes out to approximately 74.5 feet.