Answer
$\sigma = 6.00\times 10^7~(\Omega\cdot m)^{-1}$
Work Step by Step
We can find the current density:
$\sigma = \frac{J}{E}$
$J = \sigma~E$
$J = \frac{\sigma~V}{L}$
$J = \frac{(3.00\times 10^7~(\Omega\cdot m)^{-1})~(3.00~V)}{3.00\times 10^{-3}~m}$
$J = 3.00\times 10^{10}~A/m^2$
We can find the conductivity of section 1:
$\sigma = \frac{J}{E}$
$\sigma = \frac{J}{V/L}$
$\sigma = \frac{J~L}{V}$
$\sigma = \frac{(3.00\times 10^{10}~A/m^2)(4.00\times 10^{-3}~m)}{2.00~V}$
$\sigma = 6.00\times 10^7~(\Omega\cdot m)^{-1}$
