C= pi multiplied by diameter
4.
4^3 = 64
64X64 = 4096
4^6 = 4096
When you add all the numbers up and then divide by two you get the answer
<u>Answer</u>

<u>Detailed Explanation </u>
To simply answer this, since .189 has three digits we are going to be inserting 999 as the denominator since it is a repeating decimal.

We could simplify the answer!

Therefore, the answer would simply be 

<u>Always Remember </u>
In the future, always remember whenever you have a three digit decimal and the problem asks you to convert it into a fraction, you should always insert 1000 as the denominator (the numerator is basically the decimal without the decimal point) and simplify if necessary.
Let's pick some simple points with which to set up an example for ourselves for this. Let's let the smaller radius be 1, and the larger, twice that, be 2. The radius itself is a single unit measure; in other words, it's measured as inches, feet, cm, etc., while the volume is a cubed measure. Volume is measured in inches cubed, feet cubed, cm cubed, etc. Therefore, if we have the radii measuring 1:2, we simply cube those single unit measures to find the ratio of their volumes. 1 cubed is 1, and 2 cubed is 8. So your answer for this is 1/8.