Two Carrnot engines A and B are operated in series. The first one, A, receives heat at T1(= 600K) and rejects to a reservoir at temperature T2 . The second engine B receives heat rejected by the first engine and, in turn, rejects to a heat reservoir at T3(= 400K). Calculate the temperature T2 if the work outputs of the two engines are equal:
(1) 400K
(2) 600K
(3) 500K
(4) 300K