Newton's Law of Cooling: T - Ts = (T0 - Ts)ekt , where T0 = initial temperature Ts = temp of surrounding medium T = temperature at time t k = constant, t = time in minutes An object is heated to 90°C and allowed to cool in a room with a constant ambient temperature of 20°C. If after 10 minutes the temperature of the object is 60°C, a) Find k, round to 3 decimal places. b) What will its temperature be after 20 minutes?