Turn the bottle upside down for fortune telling.

I wonder if this topic is not explained in detail enough.

Suppose the bottle is a cylinder under the bottleneck, and the height under the bottleneck is more than 20 cm, which can be made into 900π ml.

The volume of water is s * h 1 = π r 2 * h 1 = 600 π.

The short water quantity is s * (h-H2) = π r 2 * (h-H2) = 300 π.

So the total volume is 900π ml.