Question

In glycerin one wood block is floating with 2/5 above the it. If wood block has 0.78 relative density then find RD OF glycerin.

Answer 1

relative density of wood= density of wood/ denisty of water
density of wood= 0.78 x 1
= 0.78

fraction of wood submerged in glycerine= 3/5

fraction of wood submerged = density of wood/ density of glycerine 
3/5= 0.78/ density of glycerine
density of glycerine= 1.3