4. The function O(W)=8e6.4can be uted te find the nunber of milians D of a cectan drue that a in a patient's bloodstream h hours atter the drug has teen adminstered a. How mawi maleraens will be present atter 4 houn? b. When the number of imililyains reaches 1 , the drug in to be adminatered acain Areer how mady hours wit the drug need to be adminiatered 5. A radioactive isotope, selenlum, hred in the creation of medical imagei of the pamoreat, has a half-ife of 115.77dan. If 300mallyams are given to a patient, how many miligams are tef after 20 days? 6. The Haleakala volcano on the idand of Mai in Hawaii is no longtr acuve. To find cut the cate of the last eruptian, sceetists conducted a chemical analyis of sanples from the velcano area. The sample1 contained apgroximately 62.31% of its original carbon-14. How lone ago sas the last eruption of the volcano? (Use 5730 years for the haltife of carbon-14)