The specific resistance of a wire is $ρ$, its volume is $3 m^3$ and its resistance is 3 ohm, then its length will be

$3/\sqrt{ρ}$

$ R = \frac{\rho l}{A}$

$ 3 =  \frac{\rho l}{A}$

$\Rightarrow \frac{A}{l} = \frac{\rho}{3}$

$\Rightarrow V = Al = 3$

$\text{Multiplying these two equations }A^2 = \rho $

$ \Rightarrow A = \sqrt \rho $

$\Rightarrow l = \frac{3}{\sqrt \rho}$