A rigid insulated cylinder is divided into two parts by a non-insulated, frictionless piston which is initially held a fixed position. One part of the cylinder contains 0.5kg of a gas at 4 bars and 30 degC, while the other part contains 1.5kg of the same gas at 1.2 bars and 30degC. The piston is then released and equilibrium established between the two parts. What is the final equilibrium pressure?