Read Example 2.46 in the textbook Links to an external site. .  Suppose a patient is given 300 mg of an anti-inflammatory medicine. The amount of medicine in the patients' body decreases exponentially, and it has a half-life in the body of 42 hours.    a) Use the half-life formula to find the decay constant k. [ Select ] k = ln(2) / (42 * 300) k = 42 * ln(2) k = e^42 k = 42 * 300* ln(2) k = ln(2) / 42 k = (300* ln(2)) / 42   b) With this value for k, what is the correct model for this situation?  [ Select ] y = 42 e^(-300 * ln(2) * t) y = 300 e^(-42/(ln(2)) * t) y = 300 e^(-(ln(2)/42) * t) y = 42 e^(-300 *42 *ln(2) * t) c) How much of the medicine is left after 6 hours? (Round to the nearest mg.)  [ Select ] 245 mg 267 mg 272 mg 211 mg 198 mg d) After how many hours is there only 10% of the medicine remaining? (Round to the nearest hour.)  [ Select ] 56 170 122 136 140多重下拉选择题