I don't agree with either of the #9 answers presented so far. I figure it like below:

"9. There are two gallon containers. One is filled with water and the other is filled with wine. Three ounces of the wine are poured into the water container. Then, three ounces from the water container are poured into the wine. Now that each container has a gallon of liquid, which is greater: the amount of water in the wine container or the amount of wine in the water container?"

Answer: The amount of wine in the water container is equivalent to the amount of water in the wine container.

Note that 1 gallon = 128 ounces.

So first three ounces of wine are poured into the water. So the wine container now contains 125 ounces of wine, and the water container now contains 128 ounces of water and 3 ounces of wine.

This is a new mixture. Now we want 3 ounces of this new mixture. Note that there are a total of 131 ounces in the counter, so 3/131 is the ratio we want to take away. To figoure out what comprises three ounces of the mixture, just take this ratio of each substance. So 3 ounces of the mixture is 3/131*128 = 384/131 ounces of water and 3/131*3=9/131 ounces of wine (note that the numerators, 384 and 9, add up to 3 times 131, so it does add up to 3 ounces).

So after removing this amount, the water container now contains 128-(384/131) = (16768/131)-(384/131) = 16384/131 ounces of water and 3-(9/131) = (393/131)-(9/131) = 384/131 ounces of wine.

Now we add the 3 ounces of mixture back to the original wine container, which previously had 125 ounces of wine. Note that this is 16375/131 ounces of wine. After adding the mixture, the wine container now contains 16375/131+9/131 = 16384/131 ounces of wine and 384/131 ounces of water.

So it works out that there is exactly as much wine in the water container as water in the wine container (the exact amount that was exchanged is 384/131).