The function T(t)=Tr + (Ti -Tr) e kt models Newton's Law of Cooling. T(t) is the temperature of a heated substance t minutes after it has been removed from a heat (or cooling) source. T_i is the substance's initial temperature, k is a constant for that substance, and Tr is room temperature.
a. The initial surface temperature of a beef roast is 236⁰F and room temperature is 72⁰F. If k=-0.041 , how long will it take for this roast to cool to 100⁰F?