Mass m of a liquid A is kept in a cup and it is at a temperature of `90^(@)C`. When placed in a room having temperature of `20^(@)C`, it takes 5 min for the temperature of the liquid to drop to `30^(@)C`. Another liquid B has nearly same density as that of A and its sample of mass m kept in another identical cup at `50^(@)C` takes 5 min for its temperature to fall to `30^(@)C` when placed in room having temperature `20^(@)C`. If the two liquids at `90^(@)C` and `50^(@)C` are mixed in a calorimeter where no heat is allowed to leak, find the final temperature of the mixture. Assume that Newton’s law of cooling is applicable for given temperature ranges.

Answer

`66^(@)`