The efficiency of a Carnot cycle is 16. By lowering the temperature of sink by 65 K, it increases to 13. The initial and final temperatures of the sink are

η = T1-T2T1= 16 --------(i)         η' = T1-(T2-65)T1 = 13---------(ii)From equations (i) and (ii)η'η= (T1-T2+65T1)(T1T1-T2) = (13)(16) = 2or T1 -T2+ 65T1-T2 = 2or T1-T2= 65--------(iii)From equation (i), 65T1= 16 or T1 = 390 Kand from equation (iii), T2-T1 - 65 = 325 K