Capacitance (Energy Stored)

Three identical capacitors P, Q and S, each of capacitance C, are connected to a battery of voltage V. Capacitors P and Q are connected in series with each other, and this series combination is connected in parallel with capacitor S across the battery. If the energy stored in capacitor P is U_P and the total energy stored in the system is U_T, then the ratio U_P/U_T is: