According to Newton's Law of Cooling, the rate of change of an object's temperature is proportional to the difference between the temperature of the object and that of the surrounding medium. The accompanying figure shows the graph of the temperature T (in degrees Fahrenheit) versus time t (in minutes) for a cup of coffee, initially with a temperature of 200F, that is allowed to cool in a room with a constant temperature of 75 F. (a) Estimate and dT/dt when t = 10 min. (b) Newton's Law of Cooling can be expressed as dT/dt=k ( proportionality and ) where k is the constant of is the temperature (assumed constant) of the surrounding medium. Use the results in part (a) to estimate the value of k