Measuring Volume of a Bottle - Investigation

Method 1) Take a "volume" measuring device, and fill it with the total amount of water, the bottle can hold. We then put the same, empty bottle into the container, in a way, that it sinks to the bottom of the akwarium. We can then measure the new height and multiply it by the volume of the liquid. This will clearly give us the volume of a bottle. Method 2) We could pour water into a 0,5 litre …

…as this was a reliable source to look at. He stated, that a body, sinked in water, would oust the same volume as the mass has. As I mentioned before, the first two methods are rather reliable, but the 3rd one brings doubts along. I am satisfied in a way, that my investigation proceeded accordingly to my plans. There weren't any noticeable problems faced. I am happy to say that this was a fair investigation.