A radioactive material disintegrates at a rate proportional tothe amount currently present. If Q(t) is the amount present at timet, then
dQ/dt=−rQ
where r>0 is the decay rate.
If 300 mg of a mystery substance decays to 80.84 mg in 3 weeks,find the time required for the substance to decay to one-half itsoriginal amount. Round the answer to 3 decimal places.
