QUESTION 9 The following graph will be used in the remaining questions of the quiz. 500 400 -300 200 100 10 15 20 25 30 35 40 45 50 A large lake has been serving as a water reservoir for a nearby town. The water had become undrinkable due to pollution of the lake by industries on the shore. The community lobbied for laws that banned further pollution. An environmental consultant was hired to assess the situation. The current concentration of pollutants in the lake is 400 ppm. Due to a combination of active remediation and natural processes, the pollution level is expected to decrease by 50% every three years. Using the formulas given in Unit 3 Chapter 1, we can find an exponential decay model for the concentration of pollutants, c(t), in ppm as a function of time, t, in years: c(t) = 400(1 /3 =400(2) -1/3 Match the following features of the graph to their corresponding meanings. - Meaning of y-intercept A. 12 years Title of x-axis B. [0,12] Title of y-axis vMathematical Domain C. The concentration of pollutants will only reach zero when the industries are shut down Practical Domain D. As the remediation efforts and natural processes continue over the years the - v Meaning of the Horizontal Asymptote (y = 0) concentration of pollutants in the lake will approach zero - The time it will take for the pollutants to reach 25 ppm E. The number of years until the concentration of the pollutants reaches zero F. The rate at which the pollutant concentration is decreasing G. [12,+inf) H. The initial concentration of pollutants in the lake, 400 ppm 1. [0, +inf) J. Time, in years K. Concentration of pollutants, in ppm L. (-inf, +inf) QUESTION 10 (just tell me the coordinates) The graph from the previous question is reproduced below. Click on the time that corresponds to a concentration that is 25% of the initial pollution level