A veteran of the war who left Southeast Asia in 1971 was tested in 1991, and it was found that her blood contained 12.5 picograms of dioxin per gram (pg/g) of blood fat. The half-life for dioxin excretion from the human body is 7.1 years. (The compound is excreted slowly but not metabolized.) Dioxin excretion follows first order kinetics. a) What was her dioxin level in 1971 when she left Vietnam? b) In what year will her dioxin level fall to the background level seen in the population of the industrialized world if that background level is 3.0 picograms per gram (pg/g) of blood fat? An exact solution to the problem is required for full credit; an estimated solution will receive partial credit.