SA and volume of half a sphere?

Hello,

I need help with volume and surface areas of half a sphere (hemispheres)

I know that v= 4/3x pi x r cubed

SA= 4x pi x r squared

However, when I do this for half a sphere, i time the answer by half and when i refer to the answers at the back of my textbook, its different. Im not sure if the sphere is open or closed, since the book doesnt state that, and are there different formulas for finding out SA and V of half open and closed spheres?

Any help is greatly appreciated.

Thanks in advance