Edexcel Paper 1 Specimen — Question 12

Exam BoardEdexcel
ModulePaper 1 (Paper 1)
SessionSpecimen
TopicExponential Equations & Modelling

  1. In a controlled experiment, the number of microbes, \(N\), present in a culture \(T\) days after the start of the experiment were counted.
    \(N\) and \(T\) are expected to satisfy a relationship of the form
$$N = a T ^ { b } , \quad \text { where } a \text { and } b \text { are constants }$$
  1. Show that this relationship can be expressed in the form $$\log _ { 10 } N = m \log _ { 10 } T + c$$ giving \(m\) and \(c\) in terms of the constants \(a\) and/or \(b\). \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{f7994129-07ee-4f6d-9531-08a15a38b794-18_1232_1046_804_513} \captionsetup{labelformat=empty} \caption{Figure 3}
    \end{figure} Figure 3 shows the line of best fit for values of \(\log _ { 10 } N\) plotted against values of \(\log _ { 10 } T\)
  2. Use the information provided to estimate the number of microbes present in the culture 3 days after the start of the experiment.
  3. Explain why the information provided could not reliably be used to estimate the day when the number of microbes in the culture first exceeds 1000000 .
  4. With reference to the model, interpret the value of the constant \(a\).