Step 1
Given;
[tex]\begin{gathered} Intially\text{ y}_0=460g \\ Half\text{ life, h=14 minutes} \\ y=\frac{460}{2}=230g,\text{ when t=h=14 min} \\ \end{gathered}[/tex]Putting these values in, we have;
[tex]\begin{gathered} 230=a(0.5)^1 \\ a=\frac{230}{0.5}=460g \end{gathered}[/tex]Therefore,
[tex]\begin{gathered} y=460(0.5)^{\frac{t}{14}}---(1) \\ when\text{ y=35} \\ 35=460(0.5)^{\frac{t}{14}} \end{gathered}[/tex][tex]\begin{gathered} 35=460(0.5)^{\frac{t}{14}} \\ \frac{460\cdot \:0.5^{\frac{t}{14}}}{460}=\frac{35}{460} \\ 0.5^{\frac{t}{14}}=\frac{7}{92} \\ \frac{t}{14}\ln \left(0.5\right)=\ln \left(\frac{7}{92}\right) \\ t=\frac{14\ln\left(\frac{7}{92}\right)}{\ln\left(0.5\right)} \\ t=52.02689 \\ t\approx52.0\text{ minutes to the nearest tenth of a minute} \end{gathered}[/tex]Answer;
[tex]52.0\text{ minutes to the nearest tenth of a minute}[/tex]