Question

Using your density calculations, what is the percent composition of copper in the penny?

Density of copper = 8.96 g/mL

Density of zinc = 7.13 g/mL

Density of penny = 2.5728 g/mL

Answer 1

if x is the percentage of copper presenting in the penny

then 1-x percentage zince presenting in penny

so total density of penny = density of copper* percentage of copper + density of zinc*percentage of zinc in penny

2.5728 g/ml = (8.96 g/mL*x)+(7.13 g/ml*(1-x))

x = -2.49 , percentage compostion is coming in negatives that means density of the penny given is wrong or not in the range it would be around 8 g/ml not 2.5728 g/ml .

please check density and substitute in place of density of penny you will get correct answer.