ASVAB (Armed Services Vocational Aptitude Battery)Arithmetic Reasoning (AR)Hard
A military base needs to store 3600 gallons of water. They have cylindrical tanks with a radius of 3 feet and a height of 7 feet. If each tank can hold approximately 198 gallons (using π ≈ 22/7), how many tanks are needed to store all the water?
- A22 tanks
- B20 tanks
- C15 tanks
- D18 tanks
Show answer & explanationAnswer & explanation
Correct answer: D. 18 tanks
First, calculate the volume of one cylindrical tank using V = π * r^2 * h. Given r=3 ft, h=7 ft, and π ≈ 22/7: V = (22/7) * (3^2) * 7 = (22/7) * 9 * 7 = 22 * 9 = 198 cubic feet. The problem states that each tank holds approximately 198 gallons, so this step is already given. To find the number of tanks needed, divide the total water by the capacity of one tank: 3600 gallons / 198 gallons/tank ≈ 18.18 tanks. Since you can't have a fraction of a tank, you need to round up to the next whole number.
Why the other options are wrong
- A. Incorrect division or over-rounding.
- B. Incorrect division or over-rounding.
- C. Incorrect division or rounding down.
Volume and Capacity Calculations
Problems that involve calculating the volume of a 3D shape and then determining how many such containers are needed for a given total capacity.
- Know basic volume formulas (e.g., cylinder V = πr²h).
- Be mindful of units (e.g., cubic feet vs. gallons, requiring conversion if not given).
- When calculating 'how many containers', always round up if there's any remainder.
Memory trick: Tank Tally: Total liquid divided by tank size, always round up!