At 550 K, the K$_c$ for the following reaction is $10^4$ mol$^{-1}$ L: $\mathrm{X(g) + Y(g) \rightleftharpoons Z(g)}$
At equilibrium, it was observed that $\mathrm{[X] = \frac{1}{2}[Y] = \frac{1}{2}[Z]}$
What is the value of [Z] (in mol L$^{-1}$) at equilibrium?