Question #14 about the resistivity of aluminum needs to be updated.  The actual resistivity of aluminum is about 2.65 x 10^-8 ohm meters.  The answer is correct given the problem but gives the resistivity to be 2.65 x 10^-11 ohm meters.  I think the person who wrote the problem made the common mistake of converting 10 mm^2 to 10 x 10^-3 m^2 instead of the correct 10 x 10^-6 m^2.  I've changed the resistance to 25 ohms and the length to 9.43 x 10^3 m.  This length is also more reasonable as the longest wire (according to Guinness) was only  24 km.