A rock of weight 17.5 N is immersed in a beaker of water while suspended from a spring scale with a reading of 9.00 N. The weight of the beaker and...

The answer is;

The net force on the beaker table  = 23.5N

In this system the weight of beaker and the weight of water are the only forces that acts on the beaker table. The other forces in this system are the weight of stone. But this does not cater the weight on the beaker table because it is suspended from a spring scale. The weight of the stone is cancelled by the force on spring scale and the up-thrust caused by the water in the beaker table. This is related to Archimedes principle. They are internal forces and it doesnot affect the force on beaker table.

How ever we need to make and assumption in this situation;

When immersing stone in the beaker water of the beaker does not flow out and it will remain in the same volume.