Here, mass of block, $m = 25\,\text{kg}$ Mass of man, $M = 50\,\text{kg}$Force applied to lift the block,$F = mg = 25 \times 10 = 250\,\text{N}.$Weight of man, $W = Mg = 50 \times 10 = 500\,\text{N}$(a) When block is raised by man as shown in figure (a), force is applied by the man in the upward direction. Action on the floor by the man $= W - F = 500 + 250 = 750\,\text{N}$(b) When block is raised by man as shown in figure (b), force is applied by the man in the downward direction. Action on the floor by the man $= W - F = 500 - 250 = 250\,\text{N}$As the floor yields to a normal force of 700 N, the mode (b) has to adopted by the man to lift the block.