1. The problem statement, all variables and given/known data When iodine is ingested by humans they eliminate it such that on half of the body's iodine content is execreted every 4.0 days. Radioactive 131I with a physical half-life of 8.1 days is administered to a patient. When will only 1% of the isotope remain in the patient's body? 2. Relevant equations 1/T1/2, e = 1/T1/2,p + 1/T1/2,b 3. The attempt at a solution I got the rest of the equation but I dont know how people got T1/2,e = 2.7 d Help please!