The formula that relates the resistance R of a wire with the resistivity [tex]\rho[/tex] of the material of the wire is
[tex]R= \frac{\rho L}{A} [/tex]
where L is the length of the wire (in our problem, [tex]L=8.2 km=8200 m[/tex]) and A is the cross sectional area (in our problem, [tex]A=4.1 \cdot 10^{-4} m^2[/tex]).
For the aluminim wire ([tex]\rho =2.82 \cdot 10^{-8} \Omega \cdot m[/tex]) of the problem, the resistance is
[tex]R= \frac{(2.82 \cdot 10^{-8}\Omega m)(8200 m)}{4.1\cdot 10^{-4}m^2}=0.564 \Omega [/tex]
