One gas of $n_1$ mole of molecules at temperature $T_1$, volume $V_1$, and pressure $P_1$, and another gas of $n_2$ mole of molecules at temperature $T_2$, volume $V_2$, and pressure $P_2$, are mixed resulting in pressure $P$ and volume $V$ of the mixture. The temperature of the mixture is . . . . . . .

• A
  $(T_1 + T_2)/2$
• B
  $(T_1 T_2 (P_1 V_1 + P_2 V_2)) / (P_1 V_1 T_2 + P_2 V_2 T_1)$
• C
  $(T_2 P_1 V_1 + T_1 P_2 V_2) / (P_1 V_1 + P_2 V_2)$
• D
  $|T_1 - T_2|/2$