A) If 170. mg of fluorine-18 is shipped at 10:00 A.M., how many milligrams of the radioisotope are still active after 330 minutes?
B) If 200. mg of fluorine-18 is shipped at 10:00 A.M., how many milligrams of the radioisotope are still active when the sample arrives at the radiology laboratory at 5:20 P.M.?