On a cold day (14degF) the furnace in an empty house stops working. If it takes 5 hours for the temperature to drop from 72degF to 61degF then how many additional hours will it take to drop down to freezing temperature? Newton's Law of Cooling says that the temperature, T(t), of the object at time t is given by T(t) = Ts + D0e^-kt where Ts is the temperature of the
surroundings and D0 is the initial temperature
difference between object and surroundings.

A) 18.3 hrs
B) 19.8 hrs
C) 21.3 hrs
D) 22.8 hrs
E) 24.3 hrs

Question

On a cold day (14degF) the furnace in an empty house stops working. If it takes 5 hours for the temperature to drop from 72degF to 61degF then how many additional hours will it take to drop down to freezing temperature? Newton's Law of Cooling says that the temperature, T(t), of the object at time t is given by T(t) = Ts + D0e^-kt where Ts is the temperature of the
surroundings and D0 is the initial temperature
difference between object and surroundings.

A) 18.3 hrs 
B) 19.8 hrs 
C) 21.3 hrs 
D) 22.8 hrs 
E) 24.3 hrs