Question: The temperature, T, in degrees Fahrenheit, of a cold yam placed in a hot oven is given by T = f(t), where t is the time in minutes since the yam was put in the oven.
(a) What is the sign of f'(t)? Why?
(b) What are the units of f'(20)? What is the practical meaning of the statement f'(20) = 2?