A hollow cylindrical conductor has length of 3.14 m, while its inner and outer diameters are 4 mm and 8 mm respectively. The resistance of the…

A hollow cylindrical conductor has length of $\displaystyle 3.14$ m , while its inner and outer diameters are $\displaystyle 4$ mm and $\displaystyle 8$ mm respectively. The resistance of the conductor is $\displaystyle n \times 10^{-3} \Omega$. If the resistivity of the material is $\displaystyle 2.4 \times 10^{-8} \Omega \mathrm{~m}$. The value of $\displaystyle n$ is $\displaystyle \_\_\_\_$.