Edexcel FD2 2019 June — Question 1

Exam BoardEdexcel
ModuleFD2 (Further Decision 2)
Year2019
SessionJune
TopicNetwork Flows

  1. Table 1 shows the cost, in pounds, of transporting one unit of stock from each of four supply points, \(\mathrm { A } , \mathrm { B } , \mathrm { C }\) and D , to each of four demand points, \(\mathrm { P } , \mathrm { Q } , \mathrm { R }\) and S . It also shows the stock held at each supply point and the stock required at each demand point. A minimum cost solution is required.
\begin{table}[h]
PQRSSupply
A1514171123
B109161242
C111381018
D1513161719
Demand25451220
\captionsetup{labelformat=empty} \caption{Table 1}
\end{table} Table 2 shows an initial solution given by the north-west corner method. \begin{table}[h]
PQRS
A23
B240
C5121
D19
\captionsetup{labelformat=empty} \caption{Table 2}
\end{table}
  1. Taking DQ as the entering cell, use the stepping-stone method to find an improved solution. Make your method clear.
  2. Perform one further iteration of the stepping-stone method to obtain an improved solution. You must make your method clear by stating the
    • shadow costs
    • improvement indices
    • route
    • entering cell and exiting cell.
    • Determine whether the solution obtained from this second iteration is optimal, giving a reason for your answer.
    • State the cost of the solution found in (b).