Chemical Equilibrium

At 600K,2‌mol of NO are mixed with 1‌mol of O2.
2NO(g)+O2(g)⇄2NO2(g)
The reaction occurring as above comes to equilibrium under a total pressure of 1‌atm. Analysis of the system shows that 0.6‌mol of oxygen are present at equilibrium. The equilibrium constant for the reaction is ____(Nearest integer)