You are given a green bottle like the image

You are given the following measurements
>diameter of the base taken from the external circumference (meaning outermost layer) = 6.5 cm
>height from the base to the top (top means where the water comes out from) = 25 cm
>diameter of the top taken from the external circumference = 2.5 cm
>diameter of the top taken from the internal circumference (meaning the innermost layer, the the inside of the bottle) = 1.8 cm
>bottle's capacity = 505 cm^3

You are challenged to find the bottle's volume.

Next, you are asked to find an equation whose graph looks like a bottle (like the one in the image) that has the same measurements.