A graduated cylinder contains 4.50 mL of water. After a piece of zinc is dropped into the cylinder, the water level rises to 9.24 mL. What is the volume of the piece of zinc?

Well, the volume of the copper is (63.4 - 40.0) * mL = 23.4 * mL

Explanation:

Do you agree? The copper displaces the given volume of water.

Now  ρ Cu =  8.90  ⋅  g  ⋅  c m 3  OR  ρ Cu  =  8.90  ⋅  g  ⋅  m L − 1, i.e.  1 ⋅  m L  ≡  1  ⋅  c m 3

But by definition,  ρ  density  =  mass  volume

And thus  mass  =  ρ  ×  volume  =  8.90  ⋅  g  ⋅  m  L  −  1  ×  23.4  ⋅  m  L

= 208.3 * G