# HOW MANY GALLONS?

How many gallons does that tank hold? Do you know how to determine the capacity of a tank? Well if you don’t, you’re about to see an easy way to find out. Before you can start to do your math, you have to know if you will be working with measurements in inches or in feet. You also have to know that the tank diameter is known as D and the tank height is H. We are looking for the tank capacity in gallons, which we will identify in our formula with the letter G.

When the measurements for a tank are expressed in inches, you will use a factor of 0.0034 in your formula. Tanks that are measured in terms of feet require a factor of 7.5. For our example, we are going to measure our tank in inches. This particular tank is 18 inches in diameter and 60 inches in height. The generic formula for this type of problem is as follows: G = d2 X h X 0.0034. We know some of the variables, so we have to put them into our equation.

The diameter of our tank is 18 inches and the height is 60 inches, so our formula will look like this: G = 182 X 60 X 0.0034. What is 182? It’s 324. This is found by multiplying 18 by itself or 18 X 18. Now we know that we are going to multiply 324 by 60 as we follow our formula. This will give us a number of 19440. The last step of our formula is to multiply 19440 by the 0.0034 factor. This will result in an answer of 66.10. We are looking for the maximum capacity of the tank, so we adjust the 66.10 to an even 66 gallons. That wasn’t too bad, was it?

CYLINDER-SHAPED CONTAINERS

cylinder-shaped containers could be tanks, pipes, or any other number of de­vices. What happens if you want to know the holding capacity of such an ob­ject? You are going to need to use a formula that involves the radius (R) of the object, the diameter of the object (D), the height (H) of the object, and the value assigned to л, which is 3.1416. Our goal is to find the volume (V) ca­pacity of a cylinder. There are two types of formulas that can be used to de­termine the capacity of a cylinder, so let’s take them one at a time.

The first formula that we are going to use looks like this: V = л r2 h. An­other way to find the answer is to have V = л divided by 4 d2 h. Either for­mula will give you the same answer, it’s just a matter of choosing one formula over another, based on your known elements of the question.