`A` test tube of thin walls has some lead shots in it at its bottom and the system floats vertically in water,sinking by a length `l_(o) = 10cm`. `A` liquid of density less than that of water, is poured into the tube till the levels inside and outside the tube are even. If the tube now sinks to a length `l_(o) = 40cm`, the specific gravity of the liquid is___.
