ρ=(m铁+m铝)/V
=(Vρ铁/6+5Vρ铝/6)/V
=[(7.9×10^3kg/m^3)+(5×2.7×10^3kg/m^3)]/6
=3.1×10^3kg/m^3
m=ρV
=3.1×10^3kg/m^3×3×10^-5m^3
=9.3×10^-2kg
=93g
ρ=(m铁+m铝)/V
=(Vρ铁/6+5Vρ铝/6)/V
=[(7.9×10^3kg/m^3)+(5×2.7×10^3kg/m^3)]/6
=3.1×10^3kg/m^3
m=ρV
=3.1×10^3kg/m^3×3×10^-5m^3
=9.3×10^-2kg
=93g