Calculating cell potential First of all, is the problem even worded correctly? From how the problem is worded, it seems that copper is being oxidized as well as iodide ion. This is what I am taught:



Second of all, I'm not getting 0.24 volts as the cell potential. I'm getting 0.19 volts. 

Here is my work. What am I doing wrong?
In electrochemistry you always write the half reaction with reduced species in the left and oxidized species on the right. This is done for consistency purposes. Species with higher potential will reduce and species with lower potential will be oxidize. 

I$_2$ + 2e- ----> 2 I$^-$   +0.54     //will reduce (go from left to right), has positive charge
Cu$^{2+}$ + 2e- ---> Cu  +0.34       //will oxidize(go from right to left), has negative charge  

Next, you should use Nernst equation to each half reaction. You will get values E$_{Cu^{2+}/Cu}$ and E$_{I_2/I^{2+}}$. Now subtract one from another to get the voltage.