Question

Iridium -192 has a half life of 74 days after 148 days, how many milligrams of 900 mg sample will remain?

Answer 1

$\bf \textit{Amount for Exponential Decay using Half-Life} \\\\ A=P\left( \frac{1}{2} \right)^{\frac{t}{h}}\qquad \begin{cases} A=\textit{accumulated amount}\\ P=\textit{initial amount}\to &900\\ t=\textit{elapsed time}\to &148\\ h=\textit{half-life}\to &74 \end{cases} \\\\\\ A=900\left( \frac{1}{2} \right)^{\frac{148}{74}}\implies A=900\left( \frac{1}{2} \right)^2\implies A=225$