Texas Commission on Environmental Quality (TCEQ). Class C Water License Exam

What is the approximate total volume of a circular tank in gallons, if it is 30 feet in diameter and 15 feet deep?

1. 60,000 gallons

2. 79,300 gallons

3. 90,000 gallons

4. 100,000 gallons

The correct answer is: 79,300 gallons

To determine the approximate total volume of a circular tank in gallons, we first need to calculate the volume in cubic feet and then convert that to gallons. The formula for the volume of a cylinder is given by: \[ \text{Volume} = \pi r^2 h \] In this case, the diameter of the tank is 30 feet, which gives a radius \( r \) of 15 feet (since the radius is half the diameter). The depth \( h \) of the tank is 15 feet. Using the formula, we calculate: 1. Calculate the area of the circular base: \[ \text{Area} = \pi (15)^2 = \pi (225) \approx 706.86 \text{ square feet} \] 2. Then, multiply by the height (depth) of the tank to find the volume in cubic feet: \[ \text{Volume} = 706.86 \times 15 \approx 10,602.9 \text{ cubic feet} \] Next, to convert cubic feet to gallons, we use the conversion factor where 1 cubic foot is approximately 7.48 gallons. 3. Therefore, converting the volume to gallons