the half life of caffeine in a healthy adult's bloodstream in 5.7 hours. suppose alex, a healthy adult, drinka a grande latte, which contains 150mg of caffeine, at 4pm. use the exponential decay model where t is the time since 4 pm measured in hours, k is exponential decay rate of caffeine and a9t) is the amount of caffeine in alex's bloodstream at time t

500 g of iodine-131 is decaying exponen- tially. After 3 days 386 g of iodine-131 is left. Use your answer from part (a) to find the half-life of iodine-131.

If the population of a Nigeria doubles in 9 years, find the growth rate k. Assume that the population increases exponentially.

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.