The temperature of equal masses of three different liquids A, B and C are 12oC, 19oC and 28oC respectively. The temperature when A and B are mixed is 16oC and when B and C are mixed is 23oC. The temperature when A and C are mixed is

Heat gain = heat lost       CA(16−12)=CB(19−16)⇒CACC=1516=54and CB(23−19)=CC(28−23)⇒CACC=54       ⇒CACC=1516              .............(i)If θ is the temperature when A and C are mixed then,           CA(θ−12)=CC(28−θ)⇒CACC=28−θθ−12 …………(ii)On solving equation (i) and (ii), θ=20.2∘C.