In 1983 the United States began coining the cent piece out of copper-clad zinc rather than pure copper. The mass of the old copper cent is $3.083 \mathrm{~g}$, whereas that of the new cent is $2.517 \mathrm{~g} .$ Calculate the percent of zinc (by volume) in the new cent. The density of copper is $8.960 \mathrm{~g} / \mathrm{cm}^{3}$, and that of zinc is $7.133 \mathrm{~g} / \mathrm{cm}^{3} .$ The new and old coins have the same volume.