1. The problem statement, all variables and given/known data The temperature, H, in degrees Celsius, of a hot cup of coffee placed on the kitchen counter is given by H=f(t), where t is in minutes since the coffee was put on the counter. Is f'(t) positive or negative? What are the units of f'(20)? What is its practical meaning in terms of the temperature of the coffee? -The rate of cooling of the coffee is 20 degrees per minute -The temperature of the coffee after 20 minutes -The temperature of the coffee is 20 degrees -The rate at which the coffee is cooling, in degrees per minute, 20 minutes after the cup is put on the counter. 2. Relevant equations 3. The attempt at a solution I'm lost.