A material has an initial of 15 units. Which equation models the amount of the material y, decaying exponentially at a rate of 23% over time x

The concentration of DDT (dichlorodiphenyltrichloroethane) in Lake Erie has been declining exponentially over the last several decades. In 1970, the DDT concentration was 13.59 ppm (parts per million). In 1985, the DDT concentration was 2.37 ppm. Part 1. Using these data points, determine the exponential decay function to model the DDT concentration decline in terms of years, tt, where t=0 represents the year 1970. (Round values to 4 decimal places)   Part 2.

Newton's Law of Cooling states that the temperature of a heated object decreases exponentially over time toward the temperature of the surrounding medium. Suppose that a pizza is removed from a 600°F oven and placed in a room whose temperature is 60°F. The temperature u (in °F) of the pizza at time t (in minutes) can be modeled by u(t)=60+540g-0.073t (a) According to the model, when will the temperature of the pizza be 500°F? (b) According to the model, when will the temperature of the pizza be 310°F? (a) t= minutes (Do not round until the final answer. Then round to the nearest minute as needed.) w an example Textbook Clear all

According to the U.S. Census Bureau, the population of the United States in 2008 was 304 million people. In addition, the population of the United States was growing at a rate of 1.1% per year. Assuming this growth rate continues, the model t- 2008 P(t) = 304 · (1.011)' represents the population P (in millions of people) in year t. According to the model, when will the population be 442 million people? Be sure to round your answer to the nearest whole year. Year