\begin{frame} \frametitle{Review - Midterm Exam 3} \begin{exampleblock}{} A bacteria culture is growing under ideal conditions and doubling every hour. If the initial population is $100$ bacteria, \pause\medskip \emph{How many bacteria will there be after half an hour?} \pause\smallskip The formula for the population is of the form $P(t) = \pause 100\cdot e^{kt}$. \pause\smallskip Let's determine $k$. \pause After $1$h we have 200 bacteria\pause, thus\vspace{-.5ex} \begin{talign} 200 = 100\cdot e^{k\cdot 1} \mpause[1]{\;\implies\; 2 = e^{k}} \mpause{\;\implies\; k = \ln 2} \end{talign}\vspace{-2.5ex} \pause\pause\pause Thus $P(t) = 100\cdot e^{t\ln 2} \pause = 100\cdot 2^{t}$. \pause After half an hour we have $\alert{100\cdot 2^{\frac{1}{2}} \approx 141}$ bacteria. \pause\medskip \emph{At what rate will the population be increasing at that point?}\\ \pause\smallskip The rate of growth is $P'(t) = 100\cdot \ln 2 \cdot 2^t$. \\\pause After half an hour the rate of growth is \alert{$100 \cdot \ln 2 \cdot 2^{\frac{1}{2}}$}. \pause\medskip \emph{When will the bacteria population reach 1000?}\vspace{-.5ex} \pause \begin{talign} 1000 = 100\cdot e^{t\ln 2} \mpause[1]{ \iff 10 = e^{t\ln 2} } \mpause{ \iff \ln 10 = t\ln 2 } \end{talign}\vspace{-3ex} \pause\pause\pause Thus after \alert{$t = \ln 10 / \ln 2 \approx 3.3$} hours. \end{exampleblock} \end{frame}