1. The? half-life of a certain substance is 30years. How long will it take for a sample of this substance to decay to 77?% of its original? amount? Use the exponential decay? model, Upper A equals Upper A 0 e Superscript kt to solve _ years.
2. The? half-life of a certain tranquilizer in the bloodstream is 3 hours. How long will it take for the drug to decay to 85?% of the original? dosage? Use the exponential decay? model, Upper A equals Upper A 0 e Superscript kt to solve. _hours