Mobilities of electrons and holes in a sample of intrinsic germanium at room temperature are $0.36m^2{V}^{-1}{s}^{-1}$ and $0.17m^2{V}^{-1}{s}^{-1}$. The electron and hole densities are each equal to $2.5\times 10^{19}{m}^3$. The electrical conductivity of germanium is

Given in question,

Mobilities of electrons${\mu }_e=0.36\times m^2{V}^{-1}{s}^{-1}$

Mobilities o holes${\mu }_h=0.17\times m^2{V}^{-1}{s}^{-1}$

densities of electron$=$ densities of holes$=2.5\times 10^{19}{m}^{-3}$

As we know, conductivity,
$\sigma =\frac{1}{p}=e({\mu }_e{n}_e+{\mu }_n{n}_n)$
$=1.6\times 10^{-19}[0.36\times 2.5\times 10^{19}+0.17\times 2.5\times 10^{19})]$
$=2.12S{m}^{-1}$

So the electrical conductivies of germanium is$2.12S{m}^{-1}$