Edexcel P3 2021 June — Question 5

Exam BoardEdexcel
ModuleP3 (Pure Mathematics 3)
Year2021
SessionJune
TopicExponential Equations & Modelling

5. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{76205772-5395-4ab2-96f9-ad9803b8388c-16_582_737_248_607} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} The growth of duckweed on a pond is being studied. The surface area of the pond covered by duckweed, \(A \mathrm {~m} ^ { 2 }\), at a time \(t\) days after the start of the study is modelled by the equation $$A = p q ^ { t } \quad \text { where } p \text { and } q \text { are positive constants }$$ Figure 1 shows the linear relationship between \(\log _ { 10 } A\) and \(t\).
The points \(( 0,0.32 )\) and \(( 8,0.56 )\) lie on the line as shown.
  1. Find, to 3 decimal places, the value of \(p\) and the value of \(q\). Using the model with the values of \(p\) and \(q\) found in part (a),
  2. find the rate of increase of the surface area of the pond covered by duckweed, in \(\mathrm { m } ^ { 2 }\) / day, exactly 6 days after the start of the study.
    Give your answer to 2 decimal places.
    \includegraphics[max width=\textwidth, alt={}, center]{76205772-5395-4ab2-96f9-ad9803b8388c-19_2649_1840_117_114}