How Long Will It Take a Sample of Radioactive Substance $\mathrm{A}(\mathrm{t})=250 \mathrm{e}^{-0.235 \mathrm{t}}$

Multiple Choice

How long will it take a sample of radioactive substance to decay to half of its original amount, if it decays according to the function $\mathrm{A}(\mathrm{t}) =250 \mathrm{e}^{-0.235 \mathrm{t}}$ , where $\mathrm{t}$ is the time in years? Round your answer to the nearest hundredth year.

A) $2.95 \mathrm{yr}$
B) $23.50 \mathrm{yr}$
C) $58.75 \mathrm{yr}$
D) $26.45 \mathrm{yr}$