Question

a raft of mass 600 kg floats on calm water with 7 cm submerged .When a man stands on the raft 8.4 cm are submerged ,the man's mass is​

Answer 1

The mass of the man is 120 kg

When an object floats on a liquid, it produced a downward force, which corresponds to the weight of the object. For balancing this force, the liquid generates an upthrust or buoyancy force on the object.  

In the above question, the mass of the man was calculated in the following manner: