The resistance R of a wire is given by:
[tex]R= \frac{\rho L}{A} [/tex]
where
[tex]\rho[/tex] is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire.
For the wire in the problem, the resistivity is (copper resistivity) [tex]\rho=1.68 \cdot 10^{-8} \Omega m[/tex]. The length of the wire is L=1.3 m, while the cross-sectional area is
[tex]A=\pi r^2 = \pi ( \frac{d}{2})^2 = \pi ( \frac{0.30 \cdot 10^{-3} m}{2} )^2 =7.07 \cdot 10^{-8} m^2[/tex]
so the resistance of the wire is:
[tex]R= \frac{(1.68 \cdot 10^{-8} \Omega m)(1.3 m)}{7.07 \cdot 10^{-8} m^2}=0.31 \Omega [/tex]
