A rigid \(2.0\text{ L}\) container holds \(0.10\text{ mol}\) of \(\text{He(g)}\) at a constant temperature, exerting a pressure of \(1.2\text{ atm}\). A sample of \(0.20\text{ mol}\) of \(\text{Ar(g)}\) is then injected into the container at the same temperature. Assuming ideal behavior, what is the total pressure inside the container after the \(\text{Ar(g)}\) is added?