199. The half-life of a substance is 8 days. After 32 days, what percentage of the nuclei of that substance remain? \[
\text{(1)}\ 6.25 \qquad \text{(2)}\ 75 \qquad \text{(3)}\ 87.50 \qquad \text{(4)}\ 93.75
\]
\textbf{199.} The half-life of a substance is 8 days. After 32 days, what percentage of the nuclei of that substance remain?
\[
\text{(1)}\ 6.25 \qquad \text{(2)}\ 75 \qquad \text{(3)}\ 87.50 \qquad \text{(4)}\ 93.75
\]