Answer
$16 e^{-0. 7195\ t}$
Work Step by Step
Recall the property $(a^m)^n=a^{mn}$, so the equation can be rewritten as $$Q=16(e^{\ln (0.487)})^t ~~~~(1)$$
Evaluating $\ln 0.487$ yields $-0. 7195$.
Therefore, the equation (1) can be written as $Q=16 (0.487)^t=16 e^{-0. 7195\ t}$