Newton s law of cooling states that for a cooling substance with initial temperature To the temperature T t after t minutes can be modeled by the equation T t T To T e kt where T is the surrounding temperature and k is the substance s cooling rate A liquid substance is heated to 80 C Upon being removed from the heat it cools to 60 C in 12 min What is the substance s cooling rate when the surrounding air temperature is 50 C Round the answer to four decimal places O 0 0687 O 0 0732 0 0813