To find the percentage of the total capacity that is being used, we need to calculate the volume of water currently in the tank and then determine what fraction of the tank's full capacity it represents.

Step 1: Find the volume of the entire tank

Since the tank is cylindrical, the volume $V$ of the entire tank can be given by the formula:

$V = \pi r^2 h$

where:

• $r$ is the radius of the base of the cylinder,
• $h$ is the height (or depth) of the tank.

From the problem, we know the diameter of the tank is 18 feet, so the radius $r$ is:

$r = \frac{18}{2} = 9 \text{ feet}$

We are not given the total height of the tank, so we will leave the height $H$ as a variable for now. The total volume of the tank is:

$V_{\text{total}} = \pi (9)^2 H = 81\pi H \text{ cubic feet}$

Step 2: Find the volume of water in the tank

The water fills the tank up to a depth of 14 feet. The volume of water in the tank is the same formula, but with the height $h = 14$:

$V_{\text{water}} = \pi (9)^2 (14) = 81\pi \times 14 = 1134\pi \text{ cubic feet}$

Step 3: Calculate the percentage of the total capacity being used

The percentage of the total capacity being used is the ratio of the volume of water to the total volume of the tank, multiplied by 100:

$\text{Percentage used} = \frac{V_{\text{water}}}{V_{\text{total}}} \times 100 = \frac{1134\pi}{81\pi H} \times 100$

The $\pi$ terms cancel out, so we have:

$\text{Percentage used} = \frac{1134}{81H} \times 100$

Simplifying:

$\text{Percentage used} = \frac{140}{H}$

Now we need the total height $H$ of the tank to finalize the calculation. Could you provide the height of the tank?