although the answers match the answer key, this question is a bit puzzling. based on the working, it means that the container is stretchable and the container volume increases (but remains as hemispherical shape) as more water is poured in.

how do you make a stretchable hemispherical container?

logically, the shape & size of the container should be fixed, and water fills the container from the bottom up, so we need to calculate the volume of the water in the container base on the depth of water, which will be much more challenging.