Take into account that the relative density is given by:
[tex]\rho_{\text{rel}}=\frac{\rho}{\rho_{\text{water}}}[/tex]
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:
[tex]\rho=\frac{\text{mass}}{\text{volume}}[/tex]
Based on table 3, you have:
mass = 50.7 g = 0.0507 kg
volume = 0.0000063 m^3
[tex]\rho=\frac{0.0507kg}{0.0000063m^3}\approx8047.62\frac{kg}{m^3}[/tex]
Then, for the relative density you obtain:
[tex]\rho_{\text{rel}}=\frac{\rho}{\rho_{\text{water}}}=\frac{8047.62\frac{kg}{m^3}}{1000\frac{kg}{m^3}}\approx8.048[/tex]
Hence, the relative density of steel is 8.048
