If the tank height is doubled to 24 feet with the same diameter, the tank capacity would be approximately how many gallons?

• A. 5,073.6 gallons
• B. 3,200 gallons
• C. 2,536.8 gallons
• D. 8,000 gallons

Answer: (A)

Volume of a cylindrical tank scales with height when the diameter stays the same. If you double the height from 12 feet to 24 feet, the volume—and thus the capacity in gallons—doubles. That means the final capacity is twice the original capacity. Since the doubling takes the volume from about 2,536.8 gallons to 5,073.6 gallons, the approximate capacity with the height at 24 feet is 5,073.6 gallons. The other numbers don’t fit this height change: they don’t reflect doubling the volume, or they represent the original capacity rather than the doubled one.