What is the density of a coin composed of zinc and copper?
From the information you've given here, you can't use these data to determine the physical composition of the pennies.
We might like to think that the alloy's density is the weighted average of the individual densities. This might even be true. However, you haven't given us the density of the coinage; this will be different than the individual densities. Given that we have no handle on the alloy composition, the answer to your question is NO.
Was that worth a wait of 5 hours? We didn't earn our money today.
I tried this but you need more information!
With only these information I think you cannor really get very far. What I did was to read about this coin and found that is copper plated so:
I considered a coin as a cylinder where the volume is made up of zinc and the surface area is copper. The problems are:
1) radius and thickness of the coin;
2) thickness of the plating.
So i tried this:
Where I got the information from the internet (radius, height and mass) and
You can solve the system to find the 2 masses BUT I do not think they will be in the right proportions...I do not know the thickness of the plating!