In making an alloy, a substance of specific gravity s1  and mass m1  is mixed with another substance of specific gravity s2  and mass m2 ; then the specific gravity of the alloy is

Specific gravity of alloy = Density of alloy  Density of water =Mass of alloy Volume of alloy×density of water  =m1+m2m1ρ1+m2ρ2×ρw=m1+m2m1ρ1/ρw+m2ρ2/ρw=m1+m2m1s1+m2s2As specific gravity of substance =density of substance density of water