Question

An element with mass 780 g decays by 17. 1% Per minute. How much of the element is remaining after 19 minutes, to the nearest 10th of a gram?

Answer 1

`\bf \qquad \textit{Amount for Exponential Decay} \\\\ A=P(1 - r)^t\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{initial amount}\dotfill &780\\ r=rate\to 17.1\%\to (17.1)/(100)\dotfill &0.171\\ t=\textit{elapsed time}\dotfill &19\ \end{cases} \\\\\\ A=780(1-0.171)^(19)\implies A=780(0.829)^(19)\implies \stackrel{\textit{rounded up}}{A = 22.1}`