6.

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{552f3296-ad61-448b-8168-6709fb359fa2-6_757_1253_262_406}
\captionsetup{labelformat=empty}
\caption{Figure 4}
\end{center}
\end{figure}

Figure 4 models a network of water pipes that need to be inspected. The number on each arc represents the length, in km , of that pipe.

A machine is to be used to inspect for leaks. The machine must travel along each pipe at least once, starting and finishing at the same point, and the length of the inspection route is to be minimised.\\[0pt]
[The total weight of the network is 185 km ]
\begin{enumerate}[label=(\alph*)]
\item Starting at A, use an appropriate algorithm to find the length of the shortest inspection route. You should make your method and working clear.

Given that it is now permitted to start and finish the inspection at two distinct vertices,
\item state which two vertices should be chosen to minimise the length of the new route. Give a reason for your answer.
\end{enumerate}

\hfill \mbox{\textit{Edexcel D1  Q6 [7]}}