7.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{23689deb-7eed-4022-848f-1278231a4056-18_614_878_296_555}
\captionsetup{labelformat=empty}
\caption{Figure 2}
\end{figure}
A chimney emits smoke particles.
On a particular day, the concentration of smoke particles in the air emitted by this chimney, \(P\) parts per million, is measured at various distances, \(x \mathrm {~km}\), from the chimney.
Figure 2 shows a sketch of the linear relationship between \(\log _ { 10 } P\) and \(x\) that is used to model this situation.
The line passes through the point ( \(0,3.3\) ) and the point ( \(6,2.1\) )
- Find a complete equation for the model in the form
$$P = a b ^ { x }$$
where \(a\) and \(b\) are constants. Give the value of \(a\) and the value of \(b\) each to 4 significant figures.
- With reference to the model, interpret the value of \(a b\)