Radioisotopes are used to diagnoa various illnesses. Iodine-131 is adminsitred to diagnoaw thyriod gland activity. Original dosage contains 280 MBq of Iodine-131. If. One is lost from body then after 6h, there r 274 MBq. What is half life of I-131 to the nearest day.

Answer 1

A = Ao (1/2)^(t/h)
274 = 280 (1/2)^(6/h)
(274/280) = (1/2)^(6/h)

This can now be solved with logarithms, but if you haven't learned those yet, trial and error is the way to go.