Answer
The investment continually decays with a rate of $ 34.6\%$ per year.
Work Step by Step
Growth/decay models have the form $Q(t)=Q_{0}e^{\pm rt}\quad \quad $
($Q_{0},k$ both positive)
with +r for growth, -r for decay.
Using the half-life formula,
$\quad t_{h}r=\ln 2$,
with the given $t_{h}=2$, we have:
$2r=\ln 2$
$r=\displaystyle \frac{\ln 2}{2}\approx 0.34657$
or, $ 34.6\%$
Thus, the investment continually decays with a rate of $ 34.6\%$ per year.
