The Lualailua Hills Quadrangle of the East Maui (Haleakala) volcano on the island of Maui in Hawaii is no longer active. To find out the date of the last eruption, scientists conducted a chemical analysis of samples from the volcano area. The samples contained approximately 62.31% of its original carbon-14. When, to the nearest year, was the last eruption of the volcano? (Use 5715 years for the half-life of carbon-14.)

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A radioactive isotope, iron-52, used in the creation of medical images of bone marrow, has a half-life of 8.2 hours. If 8 microcuries are given to a patient, how many microcuries are left after 12 hours?

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