A box contains a mixture of small copper spheres and small lead spheres

Q. A box contains a mixture of small copper spheres and small lead spheres. The total volume of both metals is measured by the displacement of water to be 427 cm3 and the total mass is 4.36 kg. What % of the spheres are copper?… I keep getting 47.1 and it says its wrong. I don’t know what I’m doing wrong.