# Hospitals use radioactive tracers in many medical tests. After the tracer is used, it must be stored as radioactive waste until its radioactivity has decreased enough for it to be disposed of as ordinary chemical waste. For the radioactive isotope iodine-131, the proportion of radioactivity remaining after t days is  e−0.087t. † How soon will the proportion of radioactivity decrease to 0.001 so that it can be disposed of as ordinary chemical waste? (Round your answer to the nearest day.) days

Question

Hospitals use radioactive tracers in many medical tests. After the tracer is used, it must be stored as radioactive waste until its radioactivity has decreased enough for it to be disposed of as ordinary chemical waste. For the radioactive isotope iodine-131, the proportion of radioactivity remaining after t days is

e−0.087t.

† How soon will the proportion of radioactivity decrease to 0.001 so that it can be disposed of as ordinary chemical waste? (Round your answer to the nearest day.)
days