A2 June 2019 Q1

EdexcelCurrent spec10 marksTransportation Problems

1. Table 1 shows the cost, in pounds, of transporting one unit of stock from each of four supply points, A, B, C and D, to each of four demand points, P, Q, 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.

PQRSSupply
A1514171123
B109161242
C111381018
D1513161719
Demand25451220

Table 1

Table 2 shows an initial solution given by the north-west corner method.

PQRS
A23
B240
C5121
D19

Table 2

(a) Taking DQ as the entering cell, use the stepping-stone method to find an improved solution. Make your method clear. (2)
(b) 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.
(4)
(c) Determine whether the solution obtained from this second iteration is optimal, giving a reason for your answer. (3)
(d) State the cost of the solution found in (b). (1)
‹ Previous7 of 7 in Transportation Problems