Newton’s law of cooling states that for a cooling substance with initial temperature t0 , the temperature t(t) after t minutes can be modeled by the equation t(t)=ts+(t0−ts)e^−kt , where ts is the surrounding temperature and k is the substance’s cooling rate. a liquid substance is heated to 80°c . upon being removed from the heat, it cools to 60°c in 15 min. what is the substance’s cooling rate when the surrounding air temperature is 50°c ? round the answer to four decimal places. a.) 0.0687 b.) 0.0732 c.) 0.0813 d.) 0.0872

The biologist has a second culture to examine. she knows that the population of the culture doubles every 15 minutes. after 1 hour and 15 minutes, her assistant found that 80,000 bacteria were present. a) what was the size of the initial population? b) predict the size of the culture at t=3 hours. what was the size of the population at 40 minutes? explain and justify your answers. c) create a graph of the population as a function of time. find an equation that can be used to predict the size of the population at any time t. d) examine the rate at which the bacteria culture is growing. how fast is the culture growing after 1 hour? after 1.5 hours? after 2 hours? use a time interval of h = 0.01 hours to estimate these rates. interpret these rates in terms of the context of the problem situation. how do these three rates compare?