## anonymous one year ago A 29 gram sample of a substance thats used for drug research has a k-value of 0.1359. N=Noe^-kt No=initial mass( at time t=0) N=mass at time t k=a positive constant that depends on the substance itself and on the units used to measure time t=time, in days Find the substance's half-life,in days.Round your answer to the nearest tenth.

1. amoodarya

$n=n_0e^{-kt}\\$

2. anonymous

im still confused

3. amoodarya

$n=n_0 e^{-0.1359t}\\n=0 \rightarrow n_0=n_0 e^0=29 gr\\n_0=29\\n=29* e^{-0.1359t}$

4. amoodarya

for a half life solve n=n0/2 $n=29* e^{-0.1359t}=\frac{n_0}{2}=\frac{29}{2}\\ e^{-0.1359t}=\frac{1}{2}\\ln\\ln( e^{-0.1359t})=\ln(\frac{1}{2})\\0.1359t=-0.6931\\t=5.100$

5. amoodarya

$t \approx 5$