2 P61186A Answer ALL questions. Write your answers in the answer book provided. 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. P Q R S Supply A 15 14 17 11 23 B 10 9 16 12 42 C 11 13 8 10 18 D 15 13 16 17 19 Demand 25 45 12 20 Table 1 Table 2 shows an initial solution given by the north-west corner method. P Q R S A 23 B 2 40 C 5 12 1 D 19 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 Ɣ shadow costs Ɣ improvement indices Ɣ route Ɣ 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) (Total for Question 1 is 10 marks)