Take into account that the relative density is given by:

where ρ, in this case, is the density of the steel and ρwater is the density of water (1000 kg/m^3).
The density of the steel is:

Based on table 3, you have:
mass = 50.7 g = 0.0507 kg
volume = 0.0000063 m^3

Then, for the relative density you obtain:

Hence, the relative density of steel is 8.048