A rod of constant cross-sectional area has conductivity κ1, and conducts heat at a constant rate between two reservoirs held at T1 and T2 respectively. It takes t1 = 8.4-s to conduct Q = 28.2-J of heat across the rod. How much time would it take to conduct the same amount of heat if half the length of the rod were replaced with a material with conductivity κ2 = n·κ1, where n = 4.5?