Radioactive strontium 90Sr has been deposited in a large field by acid rain. If sufficient amounts make their way through the food chain to humans, bone cancer can result. It has been determined that the radioactivity level in the field is 1.7 times the safe level S. 90Sr decays according to the following formula, where A0 is the amount currently in the field and t is the time in years.
A=A0e^-0.0239t
For how many years will the field be contaminated? (Round your answer to the nearest tenth.)

Question

Radioactive strontium 90Sr has been deposited in a large field by acid rain. If sufficient amounts make their way through the food chain to humans, bone cancer can result. It has been determined that the radioactivity level in the field is 1.7 times the safe level S. 90Sr decays according to the following formula, where A0 is the amount currently in the field and t is the time in years.
A=A0e^-0.0239t
For how many years will the field be contaminated? (Round your answer to the nearest tenth.)