Density homework help

Question

A chain bracelet is found. It looks as though it might be made of either gold or of copper. When the bracelet is submerged in a graduated cylinder containing water, the volume of the water rises from 9.2 cm ^ 3 to 11.7 cm ^ 3 The bracelet has a mass of 45 g. Is the bracelet made of gold or copper? (Note: The density of gold is 19.3 g/cm^ 3 and the density of copper is 8.92 g/cm^ 3 )

Answer 1

Well volume of bracelet = volume of water displaced = 11.7 - 9.2 = 2.5 cm^3

So density of bracelet = 45 / 2.5 g/cm^3 which is 18 g/cm^3

So it suggests it is a mix of gold and copper (mostly gold as the density is closest to the density of gold).

If it is g % gold, then mass of bracelet = 2.5 (g/100) x 19.3 + 2.5 ((100-g)/100) x 8.92 = 45

so you could solve this for g