The words decrease and decay indicated that r is negative. A P12 td. So 8 milligrams of radio active substance will be left after 48 days.
So 8 milligrams of radio active substance will be left after 48 days.
52 020 002 104040. P t P 0 e -rt. Exponential growth and decay often involve very large or very small numbers. In mathematics exponential decay describes the process of reducing an amount by a consistent percentage rate over a period of time.