One of the key contaminants of the nuclear accident, like that at Chernobyl, is strontium-90, that decays exponentially at the rate of approximately 2.5% per year.
Write ratio of strontium-90 remaining, P, as the function of years, t, since nuclear accident.
Evaluate half-life of strontium-90.
After Chernobyl disaster, it was predicted that region would not be safe for human habitation for 100 years. Evaluate percent of original strontium-90 remaining at this time.