Equilibrium · Degree of dissociation from kp

For the following gas phase equilibrium reaction at constant temperature,

$\ce{NH3(g) <=> 1/2 N2(g) + 3/2 H2(g)}$

If the total pressure is $\sqrt{3}$ atm and the pressure equilibrium constant ($K_\mathrm{P}$) is 9 atm, then the degree of dissociation is given as $(x\times10^{-2})^{-1/2}$.

The value of x is (Nearest integer)